r600g: texture buffer object + glsl 1.40 enable support (v2)

r600g: texture buffer object + glsl 1.40 enable support (v2)

This adds TBO support to r600g, and with GLSL 1.40 enabled,
we now get 3.1 core profiles advertised for r600g.

The r600/700 implementation is a bit different from the evergreen one,
as r6/7 hw lacks vertex fetch swizzles. So we implement it by passing 5
constants per sampler to the shader, the shader uses the first 4 as masks
for each component and the 5th as the alpha value to OR in.

Now TXQ is also broken so we have to pass a constant for the buffer size,
on evergreen we just pass this, on r6/7 we pass it as the 6th element
in the const info buffer.

v1.1: drop return as DDX doesn't use a texture type
v2: add r600/700 support.

Signed-off-by: Dave Airlie <airlied@redhat.com>