Avoid absolute install destinations

Remove use of CMAKE_INSTALL_PREFIX when specifying install destinations.
It is preferred that install destinations are specified as relative
paths, not absolute paths. This is also needed to create relocatable
installs, and thus should fix #526.

CMakeLists.txt

@@ -258,15 +258,15 @@ endif()
 ###
 ### General install settings
 ###
-set(INCLUDE_INSTALL_ROOT_DIR ${CMAKE_INSTALL_PREFIX}/include)
+set(INCLUDE_INSTALL_ROOT_DIR include)
 
 set(INCLUDE_INSTALL_DIR ${INCLUDE_INSTALL_ROOT_DIR}/yaml-cpp)
-set(LIB_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/lib${LIB_SUFFIX}")
+set(LIB_INSTALL_DIR "lib${LIB_SUFFIX}")
 
 set(_INSTALL_DESTINATIONS
-	RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}/bin
+	RUNTIME DESTINATION bin
 	LIBRARY DESTINATION ${LIB_INSTALL_DIR}
-	ARCHIVE DESTINATION "${CMAKE_INSTALL_PREFIX}/lib${LIB_SUFFIX}"
+	ARCHIVE DESTINATION ${LIB_INSTALL_DIR}
 )
 
 
@@ -320,12 +320,12 @@ configure_file(${CMAKE_CURRENT_SOURCE_DIR}/yaml-cpp-config.cmake.in
 	"${PROJECT_BINARY_DIR}/yaml-cpp-config.cmake" @ONLY)
 
 if(WIN32 AND NOT CYGWIN)
-	set(INSTALL_CMAKE_DIR ${CMAKE_INSTALL_PREFIX}/CMake)
+	set(INSTALL_CMAKE_DIR CMake)
 else()
 	set(INSTALL_CMAKE_DIR ${LIB_INSTALL_DIR}/cmake/yaml-cpp)
 endif()
 
-file(RELATIVE_PATH REL_INCLUDE_DIR "${INSTALL_CMAKE_DIR}" "${INCLUDE_INSTALL_ROOT_DIR}")
+file(RELATIVE_PATH REL_INCLUDE_DIR "${CMAKE_INSTALL_PREFIX}/${INSTALL_CMAKE_DIR}" "${CMAKE_INSTALL_PREFIX}/${INCLUDE_INSTALL_ROOT_DIR}")
 set(CONFIG_INCLUDE_DIRS "\${YAML_CPP_CMAKE_DIR}/${REL_INCLUDE_DIR}")
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/yaml-cpp-config.cmake.in
 	"${PROJECT_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/yaml-cpp-config.cmake" @ONLY)