cmake openmp define change

git-svn-id: http://www.openflipper.org/svnrepo/OpenFlipper/branches/Free@5607 383ad7c9-94d9-4d36-a494-682f7c89f535

common/GlobalDefines.hh

@@ -65,9 +65,11 @@
 
 /** Enable openmp where possible (for gcc version >= 4.3)
  */
+#ifndef USE_OPENMP
   #if GCC_VERSION >= 4030
     #define USE_OPENMP
   #endif
+#endif
 
 
 #ifndef DLLEXPORT