Added intel architecture detection so SSE/AVX isn't enabled when it shouldn't be.

dlib/cmake

@@ -23,10 +23,13 @@ if (CMAKE_COMPILER_IS_GNUCXX)
     add_global_compiler_switch(-Wreturn-type)
 endif()
 
+
+set(gcc_like_compilers GNU Clang  Intel)
+set(intel_archs x86_64 i386)
+
 # Setup some options to allow a user to enable SSE and AVX instruction use.  
-if (CMAKE_COMPILER_IS_GNUCXX OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" 
-                                OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU"
-                                OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "Intel")
+if ((";${gcc_like_compilers};" MATCHES ";${CMAKE_CXX_COMPILER_ID};") AND
+    (";${intel_archs};"        MATCHES ";${CMAKE_SYSTEM_PROCESSOR};"))
     option(USE_SSE2_INSTRUCTIONS "Compile your program with SSE2 instructions" OFF)
     option(USE_SSE4_INSTRUCTIONS "Compile your program with SSE4 instructions" OFF)
     option(USE_AVX_INSTRUCTIONS  "Compile your program with AVX instructions"  OFF)