vc4: Add support for sampling from sRGB.

This isn't perfect -- the filtering is happening on the srgb values, and
we're decoding afterwards, which is not what you want.  I think that's the
cause of some additional texwrap(GL_CLAMP, LINEAR) failures, though many
other texwrap tests on srgb start to pass since unfiltered values come out
correct.
vc4: Add support for framebuffer sRGB encoding.
radeonsi: Clear sampler view flags when binding a buffer

Fixes assertion failure while running the Unreal Engine 4 Elemental demo:

.../si_blit.c:322:si_decompress_color_textures: Assertion `tex->cmask.size || tex->fmask.size' failed.

Cc: "10.2 10.3" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
freedreno/ir3: add IDIV/UDIV support

Logic shamelessly copied from nv50 lowering pass.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
freedreno/ir3: add UMOD support, based on UDIV

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
freedreno/ir3: add MOD support

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
freedreno/ir3: add ISSG support

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
freedreno/ir3: add UMAD support

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
freedreno/ir3: make TXQ return integers, not floats

We're still doing something wrong for array textures.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
freedreno/ir3: shadow comes before array

Experimentally, this makes *ArrayShadow tex-miplevel-selection tests
pass.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
freedreno/ir3: add texture offset support

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
freedreno/ir3: add TXD support and expose ARB_shader_texture_lod

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
freedreno/ir3: add TXF support

Still failing a bunch of the fairly picky texelFetch tests, but the
1D(Array) ones are full passes.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>