cmTime.h: Added OSX specfic clock_gettime().

cmTime.h

@@ -7,10 +7,13 @@
 // calculate elapsed time.
 //)
 
+#ifdef OS_OSX
+#include "osx/clock_gettime_stub.h"
+#endif
+
 #ifndef cmTime_h   
 #define cmTime_h
 
-
 #ifdef __cplusplus
 extern "C" {
 #endif