st/mesa: avoid exposing EXT_texture_integer for pre-GLSL 1.30

For drivers building up to GL(ES)3, only expose the actual extension if
the API will let it be used (e.g. via overrides/debug flags that enable
higher versions).

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
freedreno/a4xx: invalidate cache when vbo's change

Otherwise vertex shader can see stale cache data.  This in particular
happens when the same vbo is updated and reused.  Not sure yet if vbo's
at differing addresses but bound to same vertex buffer slot could have
issues, but seems safest to flush whenever new vertex buffers are bound.

Signed-off-by: Rob Clark <robclark@freedesktop.org>