Flipped the include guard and the pragma, and don't use the pragma for early...

Flipped the include guard and the pragma, and don't use the pragma for early versions of gcc (< 3.4)

include/yaml-cpp/aliasmanager.h

-#pragma once
-
 #ifndef ALIASMANAGER_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define ALIASMANAGER_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 #include "yaml-cpp/anchor.h"
 #include <map>
 

include/yaml-cpp/anchor.h

-#pragma once
-
 #ifndef ANCHOR_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define ANCHOR_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 #include <cstddef>
 
 namespace YAML

include/yaml-cpp/contrib/anchordict.h

-#pragma once
-
 #ifndef ANCHORDICT_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define ANCHORDICT_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 #include <vector>
 
 #include "../anchor.h"

include/yaml-cpp/contrib/graphbuilder.h

 #ifndef GRAPHBUILDER_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define GRAPHBUILDER_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 #include <string>
 
 namespace YAML

include/yaml-cpp/conversion.h

-#pragma once
-
 #ifndef CONVERSION_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define CONVERSION_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 #include "yaml-cpp/null.h"
 #include "yaml-cpp/traits.h"

include/yaml-cpp/emitfromevents.h

-#pragma once
-
 #ifndef EMITFROMEVENTS_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define EMITFROMEVENTS_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 #include "yaml-cpp/eventhandler.h"
 #include <stack>
 

include/yaml-cpp/emitter.h

-#pragma once
-
 #ifndef EMITTER_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define EMITTER_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 #include "yaml-cpp/emittermanip.h"
 #include "yaml-cpp/ostream.h"

include/yaml-cpp/emittermanip.h

-#pragma once
-
 #ifndef EMITTERMANIP_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define EMITTERMANIP_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 #include <string>
 

include/yaml-cpp/eventhandler.h

-#pragma once
-
 #ifndef EVENTHANDLER_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define EVENTHANDLER_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 #include "yaml-cpp/anchor.h"
 #include <string>
 

include/yaml-cpp/exceptions.h

-#pragma once
-
 #ifndef EXCEPTIONS_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define EXCEPTIONS_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 #include "yaml-cpp/mark.h"
 #include "yaml-cpp/traits.h"

include/yaml-cpp/iterator.h

-#pragma once
-
 #ifndef ITERATOR_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define ITERATOR_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 namespace YAML
 {

include/yaml-cpp/mark.h

-#pragma once
-
 #ifndef MARK_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define MARK_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 namespace YAML
 {

include/yaml-cpp/node.h

-#pragma once
-
 #ifndef NODE_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define NODE_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 #include "yaml-cpp/conversion.h"
 #include "yaml-cpp/exceptions.h"

include/yaml-cpp/nodeimpl.h

-#pragma once
-
 #ifndef NODEIMPL_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define NODEIMPL_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 #include "yaml-cpp/nodeutil.h"
 

include/yaml-cpp/nodeproperties.h

-#pragma once
-
 #ifndef NODEPROPERTIES_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define NODEPROPERTIES_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 namespace YAML
 {
 	struct NodeProperties {

include/yaml-cpp/nodereadimpl.h

+#ifndef NODEREADIMPL_H_62B23520_7C8E_11DE_8A39_0800200C9A66
+#define NODEREADIMPL_H_62B23520_7C8E_11DE_8A39_0800200C9A66
+
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
 #pragma once
+#endif
+
 
 namespace YAML
 {
@@ -76,3 +82,5 @@ namespace YAML
 		return Convert(scalar, value);
 	}
 }
+
+#endif // NODEREADIMPL_H_62B23520_7C8E_11DE_8A39_0800200C9A66

include/yaml-cpp/nodeutil.h

-#pragma once
-
 #ifndef NODEUTIL_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define NODEUTIL_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 namespace YAML
 {

include/yaml-cpp/noncopyable.h

-#pragma once
-
 #ifndef NONCOPYABLE_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define NONCOPYABLE_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 namespace YAML
 {

include/yaml-cpp/null.h

-#pragma once
-
 #ifndef NULL_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define NULL_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 namespace YAML
 {

include/yaml-cpp/ostream.h

-#pragma once
-
 #ifndef OSTREAM_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 #define OSTREAM_H_62B23520_7C8E_11DE_8A39_0800200C9A66
 
+#if !defined(__GNUC__) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || (__GNUC__ >= 4) // GCC supports "pragma once" correctly since 3.4
+#pragma once
+#endif
+
 
 #include <string>