This is a (partial) backport of the signed texture format support in OGL 3.1.
Since it wasn't promoted from an existing extension roll our own.

add new entrypoints, new texture format, etc
translate in texenvprogram.c for drivers using the mesa-generated tex env
fragment program
also handled in swrast, but not tested (cannot work due to negative texel
results not handled correctly)

The TexSubImage commands do not have the "NULL image" flag that was
introduced with glTexImage3D.  However, there is a CARD32 pad element
where that flag would be.  Removing the img_null_flag causes the flag
to be removed from the protocol.  This changes the protocol and breaks
everything.

In order to prevent needing to hand-code all of the TexSubImage
functions, a new attribute was added to the param element.  This new
attribute, called "padding," is a boolean flag that selects whether or
not the parameter is a real parameter (default / false) or is protocol
padding (true) that does not appear in the function's parameter list.

This change resulted in a number of changes to other Python scripts.
In almost all cases parameters with the is_padding flag set should not
be emitted.

This patch only changes the the XML, the DTD, and the generator
scripts.  It does NOT include the resulting changes to the generated
code.  Generated code in the X server is also changed by the script /
XML changes in this patch.

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

See bug 18445.
When getting array results, __glXReadReply() always reads a multiple of
four bytes.  This can cause writing to invalid memory when 'n' is not a
multiple of four.

Special-case the glAreTexturesResident() functions now.
To fix the bug, we use a temporary buffer that's a multiple of four bytes
in length.

NOTE: this commit also reverts part of commit 919ec22ecf72aa163e1b97d8c7381002131ed32c
(glx/x11: Added some #ifdef GLX_DIRECT_RENDERING protection) which
directly edited the indirect.c file rather than the python generator!
I'm not repairing that issue at this time.