Make releaseCGLContext a no-op

It is sometimes called after the context is destroyed. Attempting to call any
gl* functions in this case causes a segfault.

gl-natives/src/main/c/jaggl.c

@@ -327,11 +327,15 @@ static void *jaggl_proc_addr(const char *name) {
 }
 
 - (void)releaseCGLContext:(CGLContextObj)context {
-	CGLSetCurrentContext(context);
+	/*
-	[lock lock];
+	 * Ideally we'd delete the framebuffer/renderbuffers here, if they exist.
-	[self deleteFramebuffer];
+	 * However, releaseCGLContext sometimes ends up being called after we
-	[lock unlock];
+	 * destroy the jaggl_onscreen_context, so attempting to call any gl*
-	CGLClearDrawable(context);
+	 * functions here causes a segfault.
+	 *
+	 * Hopefully deleting the context will free up the
+	 * framebuffer/renderbuffers implicitly.
+	 */
 }
 @end
 #endif