GL_QCOM_alpha_test
https://www.khronos.org/registry/OpenGL/extensions/QCOM/QCOM_alpha_test.txt
GL_ALPHA_TEST_QCOM 0x0BC0
GL_ALPHA_TEST_FUNC_QCOM 0x0BC1
GL_ALPHA_TEST_REF_QCOM 0x0BC2
void glAlphaFuncQCOM (GLenum func, GLclampf ref)