arb_compute_shader: Add test for double-precision arithmetic in combination with large group size.

Large enough group sizes require SIMD32 code generation on recent
Intel hardware, which has regressed several times in master in
combination with 64-bit types.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111566
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
8 jobs for arb_compute_shader-fp64-simd32 in 8 minutes and 43 seconds (queued for 1 second)
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