llvmpipe: hack-fix bugs due to bogus bind flags

llvmpipe: hack-fix bugs due to bogus bind flags

The gallium contract would be that bind flags must indicate all possible
bindings a resource might get used, but fact is the mesa state tracker does
not set bind flags correctly, and this is more or less unfixable due to GL.

This caused a bug with piglit arb_uniform_buffer_object-rendering-dsa
since 6e6fd911da8a1d9cd62fe0a8a4cc0fb7bdccfe02 - the commit is correct,
but it caused us to miss updates to fs UBOs completely, since the
corresponding buffer didn't have the appropriate bind flag set (thus we
wouldn't check if it is indeed currently bound).
See the discussion about this starting here:
https://lists.freedesktop.org/archives/mesa-dev/2016-June/119829.html

So, update the bind flags when we detect such usage.
Note we update this value for now only in places which matter for us - that
is creating sampler/surface view, or binding constant buffer. There's plenty
more places (setting streamout buffers, vertex/index buffers, ...) where
things can be set with the wrong bind flags, but the bind flags there never
matter.

While here also make sure we only set dirty constant bit when it's a fs
constant buffer - totally doesn't matter if it's vs/gs.

Reviewed-by: Jose Fonseca <jfonseca@vmware.com>