mesa: Drop PATH_MAX usage.

mesa: Drop PATH_MAX usage.

GNU/Hurd does not define PATH_MAX since it doesn't have such arbitrary
limitation, so this failed to compile.  Apparently glibc does not
enforce PATH_MAX restrictions anyway, so it's kind of a hoax:

https://www.gnu.org/software/libc/manual/html_node/Limits-for-Files.html

MSVC uses a different name (_MAX_PATH) as well, which is annoying.

We don't really need it.  We can simply asprintf() the filenames.
If the filename exceeds an OS path limit, presumably fopen() will
fail, and we already check that.  (We actually use ralloc_asprintf
because Mesa provides that everywhere, and it doesn't look like we've
provided an implementation of GNU's asprintf() for all platforms.)

Fixes the build on GNU/Hurd.

Cc: "13.0" <mesa-stable@lists.freedesktop.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98632
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>