gl/cocoa: fix compiler warning
Use the reshape function after being defined. The other way would have been to declare the reshape function in the header. gstglwindow_cocoa.m: In function '-[GstGLNSView drawRect:]': gstglwindow_cocoa.m:555: warning: 'GstGLNSView' may not respond to '-reshape' gstglwindow_cocoa.m:555: warning: (Messages without a matching method signature gstglwindow_cocoa.m:555: warning: will be assumed to return 'id' and accept gstglwindow_cocoa.m:555: warning: '...' as arguments.)