glapi: Add es1 and es2 attributes to XML.

glapi: Add es1 and es2 attributes to XML.

Currently, the set of functions which exist in GLES1 or GLES2 is
determined by hardcoded lists of function names in gles_api.py.  This
patch encodes that information into the XML files using new
attributes, es1 and es2.

The es1 attribute denotes the first version of GLES 1 in which the
function exists (e.g. es1="1.1" means the function exists in GLES 1.1
but not GLES 1.0).  "none" (the default) means the function is not
available in any version of GLES 1.

The es2 attribute denotes the first version of GLES 2/3 in which the
function exists (e.g. es2="2.0" means the function exists in both GLES
2.0 and GLES 3.0).  "none" (the default) means the function is not
available in any version of GLES 2 or GLES 3.

Note that since GLES 3 is a strict superset of GLES 2, there is no
need for a separate attribute for it; instead, 'es2="3.0"' should be
used to denote functions that are present in GLES 3 but not GLES 2.

This patch only adds information about GLES versions 1.0, 1.1, and
2.0.

Later patches will modify the python code generation scripts to use
this information rather than the hardcoded lists in gles_api.py.

Tested-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>