Check for clang instead of apple to know it must include openMP, as clang...

Check for clang instead of apple to know it must include openMP, as clang don't support it on any platform. Easea now compile on clang/llvm 3.0 and 3.3

libeasea/include/CComUDPLayer.h

@@ -22,7 +22,7 @@
 #include <typeinfo>
 #include <float.h>
 #include <limits.h>
-#if not defined(__APPLE__) 
+#ifndef __clang__
 #include <omp.h>
 #endif
 #include <string>