drirc: Disable ARB_blend_func_extended for Heaven 4.0/Valley 1.0.

drirc: Disable ARB_blend_func_extended for Heaven 4.0/Valley 1.0.

Unigine Heaven 4.0 and Valley 1.0 use dual color blending but don't
specify which fragment shader output is which, so there's at best a
50/50 chance of us guessing it correctly.  This is invalid.

Unigine fixed this in 4.1 and 1.1 versions over a year and a half ago,
but hasn't actually released them for whatever reason.  So, add the
workaround back so that it works for most people.

Fixes Heaven 4.0/Valley 1.0 rendering on Ivybridge.  For whatever
reason, Broadwell worked.  4.1 and 1.1 have always worked.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92233
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Cc: mesa-stable@lists.freedesktop.org