GL_SGIS_multisample
http://oss.sgi.com/projects/ogl-sample/registry/SGIS/multisample.txt
	GL_MULTISAMPLE_SGIS 0x809D
	GL_SAMPLE_ALPHA_TO_MASK_SGIS 0x809E
	GL_SAMPLE_ALPHA_TO_ONE_SGIS 0x809F
	GL_SAMPLE_MASK_SGIS 0x80A0
	GL_1PASS_SGIS 0x80A1
	GL_2PASS_0_SGIS 0x80A2
	GL_2PASS_1_SGIS 0x80A3
	GL_4PASS_0_SGIS 0x80A4
	GL_4PASS_1_SGIS 0x80A5
	GL_4PASS_2_SGIS 0x80A6
	GL_4PASS_3_SGIS 0x80A7
	GL_SAMPLE_BUFFERS_SGIS 0x80A8
	GL_SAMPLES_SGIS 0x80A9
	GL_SAMPLE_MASK_VALUE_SGIS 0x80AA
	GL_SAMPLE_MASK_INVERT_SGIS 0x80AB
	GL_SAMPLE_PATTERN_SGIS 0x80AC
	GL_MULTISAMPLE_BIT_EXT 0x20000000
	void glSampleMaskSGIS (GLclampf value, GLboolean invert)
	void glSamplePatternSGIS (GLenum pattern)