mapi: Hack around glGetInternalformativ not being hidden in GLES

mapi: Hack around glGetInternalformativ not being hidden in GLES

This is hella ugly.  The same-named function in desktop OpenGL is
hidden, but it needs to be exposed by libGLESv2 for OpenGL ES 3.0.
There's no way to express in the XML that a function should be be hidden
in one API but exposed in another.

This won't affect any change now, but it will prevent a regression in a
later patch.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>