mesa: save/restore SSO flag when using ARB_get_program_binary

Without this the restored program will fail the pipeline validation
checks when we attempt to use an SSO program.

Fixes: c20fd744 ("mesa: Add Mesa ARB_get_program_binary helper functions")

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111010
(cherry picked from commit 3043908c)