Fixes build failure on Mac OS X 10.10 Yosemite Beta due to highgui/src/window_cocoa.mm (Bug #3737)

modules/highgui/src/window_cocoa.mm

@@ -151,7 +151,7 @@ CV_IMPL int cvInitSystem( int , char** )
 #define NSAppKitVersionNumber10_5 949
 #endif
     if( floor(NSAppKitVersionNumber) > NSAppKitVersionNumber10_5 )
-        [application setActivationPolicy:0/*NSApplicationActivationPolicyRegular*/];
+        [application setActivationPolicy:NSApplicationActivationPolicyRegular];
 #endif
     //[application finishLaunching];
     //atexit(icvCocoaCleanup);