GLES2: Add a runtime check for occlusion query support
GLES2: Add a runtime check for occlusion query support

--HG--
branch : v1-8

ruleless/ogre,ruleless/ogre,ehsan/ogre,bhlzlx/ogre,bhlzlx/ogre,bhlzlx/ogre,bhlzlx/ogre,ruleless/ogre,ehsan/ogre,ruleless/ogre,ehsan/ogre,ruleless/ogre,ehsan/ogre,bhlzlx/ogre,ehsan/ogre,ruleless/ogre,bhlzlx/ogre