i965: Enable several GLES 3.1 extensions on HSW+

The only reason we didn't previously enable this was the dependency on
OpenGL ES 3.1.  These should have been enabled as soon as HSW got
stencil texturing.  We also needed to fixup setting MaxViewports.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
3 files changed