fix for using system includes, the include macro wasn't un-setting the previous include list so system includes could be mixed up with non system includes.

Also workaround for CMake 2.8.4 & GNU-Make which doesn't set CMAKE_INCLUDE_SYSTEM_FLAG_C

build_files/cmake/FindPythonLibsUnix.cmake

@@ -53,8 +53,17 @@ if(NOT DEFINED PYTHON_INCLUDE_DIRS)
 	if(NOT _Found_PYTHON_H)
 		message(FATAL_ERROR "Python.h not found")
 	endif()
+	
+	unset(_Found_PYTHON_H)
+	unset(_Python_HEADER)
+	unset(_CURRENT_ABI_FLAGS)
+	unset(_CURRENT_PATH)
+	
 endif()
 
+unset(_Python_ABI_FLAGS)
+unset(_Python_PATHS)
+
 #=============================================================================
 # now the python versions are found