glsl: Use a stable attr sort for VS in / FS out
This is a perpetual bug that hits Windows. In the MSVC CRT, qsort is unstable, where the glibc qsort is stable. So apps run fine on Windows IHV drivers, and on Linux Mesa drivers, and only break down when running on Windows Mesa drivers.
Closes: #10922 (closed) See also !22800 (closed) and #10637