glx: Enable GLX_EXT_create_context_es2_profile

glx: Enable GLX_EXT_create_context_es2_profile

This extension is only enabled if the underlying driver advertises
support for OpenGL ES 2.0.  This happens either through the getAPIMask
function in version 2 of the DRI2 extension or implicity through
version 2 of the DRISW extension.

Since there is no OpenGL ES 2.0 protocol, this extension is marked as
only available with direct-rendering.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>