_mesa_create_exec_table: GLES3 fixes.  TODO: merge ClampColor first.  TODO: fix api_loopback.h warning.

This patch sets up the dispatch table for the following functions when
a GLES3 context is in use:

- BeginQuery
- BeginTransformFeedback
- BindSampler
- BindTransformFeedback
- BlitFramebuffer
- ClearBufferfi
- ClearBufferfv
- ClearBufferiv
- ClearBufferuiv
- ClientWaitSync
- CopyBufferSubData
- DeleteQueries
- DeleteSamplers
- DeleteSync
- DeleteTransformFeedbacks
- EndQuery
- EndTransformFeedback
- FenceSync
- FramebufferTextureLayer
- GenQueries
- GenSamplers
- GenTransformFeedbacks
- GetInteger64v
- GetQueryObjectuiv
- GetQueryiv
- GetSamplerParameterfv
- GetSamplerParameteriv
- GetStringi
- GetSynciv
- GetTransformFeedbackVarying
- GetVertexAttribIiv
- GetVertexAttribIuiv
- IsQuery
- IsSampler
- IsSync
- IsTransformFeedback
- PauseTransformFeedback
- RenderbufferStorageMultisample
- ResumeTransformFeedback
- SamplerParameterf
- SamplerParameterfv
- SamplerParameteri
- SamplerParameteriv
- TransformFeedbackVaryings
- VertexAttribIPointer
- WaitSync

And it avoids setting up the dispatch table for these non-GLES3 functions:

- ColorMaski
- GetBooleani_v
- Enablei
- Disablei
- IsEnabledi
- ClearColorIiEXT
- ClearColorIuiEXT
- TextureStorage2DEXT
- TextureStorage3DEXT

Cc: Matt Turner <mattst88@gmail.com>
_mesa_create_exec_table: GLES1 fixes.  TODO: more.

Currently, _mesa_create_exec_table() (in api_exec.c) is used for all
APIs except GLES1.  In GLES1, _mesa_create_exec_table_es1() (a code
generated function) is used instead.

In principle, this shouldn't be necessary.  It should be possible for
api_exec.c to contain the logic for populating the dispatch table for
all API's.

This patch paves the way for using _mesa_create_exec_table() instead
of _mesa_create_exec_table_es1(), by making _mesa_create_exec_table()
(and the functions it calls) expose the correct subset of desktop GL
functions for GLES1.

Unfortunately, we can't switch over to _mesa_create_exec_table() quite
yet.
glapi: Alias ClampColor and ClampColorARB.

There's no reason to have separate slots in the dispatch table for
these two functions, since they are synonymous.
WIP: mark stuff as deprecated
WIP: mark more stuff as deprecated
WIP: mark more stuff as deprecated
Whoops, erroneously marked DrawBuffer as deprecated
Whoops, StencilFuncSeparateATI should be deprecated, not StencilFuncSeparate.
Whoops, PolygonOffsetEXT should be deprecated, not PolygonOffset
Never mind, GetPointerv shouldn't be deprecated.
glapi: use GL_ or GLX_ prefix for all category names.

This patch standardizes the category names used in the glapi XML files
to begin each extension name with the prefix "GL_" or "GLX_".  There
is no functional change, because these category names are not used in
the generated code.
Deprecate TexBumpParameter{if}vATI, since we already depreacte the other functions in ATI_envmap_bumpmap (and the extension itself)
Whoops, I think StencilFuncSeparateATI should not be deprecated
Oops, ProgramStringARB should be deprecated
HACK: remove #if 0 blocks from api_exec.c
HACK: remove comments from api_exec.c
HACK: remove blank lines from api_exec.c
HACK: manually inline functions
WIP: De-static loopback functions.  TODO: move earlier.
WIP: de-static _mesa_Accum