I have added a few new configuration files to the configs directory:

    There's a base configuration, debian, which sets things up for
    building in a debian environment.

    There's also a debian-static configuration, which is for static
    building.

All the others are derived from one of these two configurations.

The platform-specific optimizations go into a debian-foo_ARCH file, like
debian_i386 or debian_sparc.  You can name this files whatever you want,
but the last token must be a debian arch name.  Note the "_"!  These
will be picked up automatically by the debian/rules.

In order to actually install the new files, you need to edit
debian/libdir.map, the format is:

    target-name libdir package package-dev

The architecture optimized libraries should go under
/usr/lib/<something>, where <something> matches the optimizations used,
e.g. "cmov" or "v9".

Only packages listed in the control file *and* libdir.map are actually
built.  That means that even if debian/libdir.map lists
libgl1-random-stuff, if libgl1-random-stuff is *not* listed in
debian/control it *won't* be built.  The other way around, if
libgl1-random-stuff is listed in debian/control but there's no entry for
it in debian/libdir.map it *won't* be built.

Again...

If the libdir.map file doesn't mention your (lib)-(config), e.g.
gl-debian_i386, THE TARGET WON'T BE BUILT.

If the package listed in libdir.map is not listed in debian/control, THE
TARGET WON'T BE BUILT.

For architectures where glide3 is available an extra package is built
(iff this is the mesa-legacy source package).  The list of supported
architectures in found in the control file.

There's an alioth project for this package:
http://alioth.debian.org/projects/pkg-mesa/