Cleanup and use core graphics directly to swap buffers rather than going though the overhead of the obj-c calls.

stepmania/src/arch/LowLevelWindow/LowLevelWindow_Cocoa.mm

@@ -409,8 +409,7 @@ void LowLevelWindow_Cocoa::GetDisplayResolutions( DisplayResolutions &dr ) const
 
 void LowLevelWindow_Cocoa::SwapBuffers()
 {
-	// XXX don't use Obj-C here, use CG.
-	[[NSOpenGLContext currentContext] flushBuffer];
+	CGLFlushDrawable( CGLGetCurrentContext() );
 }
 
 void LowLevelWindow_Cocoa::Update()
@@ -430,7 +429,6 @@ void LowLevelWindow_Cocoa::Update()
 
 void LowLevelWindow_Cocoa::BeginConcurrentRendering()
 {
-	LOG->Trace( __func__ );
 	if( m_CurrentParams.windowed )
 		[m_BGContext setView:[m_Window contentView]];
 	else
@@ -440,7 +438,6 @@ void LowLevelWindow_Cocoa::BeginConcurrentRendering()
 
 void LowLevelWindow_Cocoa::EndConcurrentRendering()
 {
-	LOG->Trace( __func__ );
 	[NSOpenGLContext clearCurrentContext];
 	[m_BGContext clearDrawable];
 }