It's been regressed a couple of times recently, so let's try to make sure
it doesn't happen again.  The setup here is mostly like llvmpipe-quick-gl,
but using quick_gl+quick_shader together, and a few more spectacularly
long-running tests dropped.  I also excluded a bunch of unsupported
extensions, to minimize the size of the skip list checked into the tree
(it's still 200k, though).

The unfortunate exclusions in here are fp64 and int64 -- most of the
piglit tests for them don't run because softpipe is still GL3.3, and it's
an egregious number of skips to add to the checked in list.

Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <mesa/mesa!8068>