(untested) fix vsync on osx

stepmania/src/RageDisplay_OGL_Extensions.cpp

@@ -89,7 +89,7 @@ void GLExt_t::Load( LowLevelWindow *pWind )
 	if( HasExtension("WGL_EXT_swap_control") )
 		wglSwapIntervalEXT = (PWSWAPINTERVALEXTPROC) pWind->GetProcAddress("wglSwapIntervalEXT");
 #elif defined(MACOSX)
-	wglSwapIntervalEXT = wglSwapIntervalEXT;
+	wglSwapIntervalEXT = OSXSwapIntervalEXT;
 #endif
 
 	if( HasExtension("GL_EXT_paletted_texture") )

stepmania/src/archutils/Darwin/Vsync.cpp

@@ -2,7 +2,7 @@
 #include <OpenGl/OpenGl.h>
 
 
-bool wglSwapIntervalEXT( int swapInterval )
+bool OSXSwapIntervalEXT( int swapInterval )
 {
     return !CGLSetParameter( CGLGetCurrentContext(), kCGLCPSwapInterval, (long*)(&swapInterval) );
 }

stepmania/src/archutils/Darwin/Vsync.h

@@ -1,7 +1,7 @@
 #ifndef VSYNC_H
 #define VSYNC_H
 
-bool wglSwapIntervalEXT( int swapInterval );
+bool OSXSwapIntervalEXT( int swapInterval );
 
 #endif