intel/fs: Stop stack allocating large arrays

Normally, we haven't worried too much about stack sizes as Linux tends
to be fairly friendly towards large stacks.  However, when running DXVK
apps under wine, we're suddenly subject to Windows' more stringent stack
limitations and can run out of space more easily.  In particular, some
of the shaders in Elite Dangerous: Horizons have quite a few registers
and the arrays in split_virtual_grfs are large enough to blow a 1 MiB
stack leading to crashes during shader compilation.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108662


Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Cc: mesa-stable@lists.freedesktop.org
(cherry picked from commit fa63fad3)