GL_SGIX_async
http://www.opengl.org/registry/specs/SGIX/async.txt
GL_SGIX_async
	GL_ASYNC_MARKER_SGIX 0x8329
	void glAsyncMarkerSGIX (GLuint marker)
	void glDeleteAsyncMarkersSGIX (GLuint marker, GLsizei range)
	GLint glFinishAsyncSGIX (GLuint* markerp)
	GLuint glGenAsyncMarkersSGIX (GLsizei range)
	GLboolean glIsAsyncMarkerSGIX (GLuint marker)
	GLint glPollAsyncSGIX (GLuint* markerp)