mesa: allow internalformat_query with multisample texture targets

Now that we support ARB_texture_multisample, there are multiple targets
accepted for this query, and they may have target-dependent limits, so
pass the target to the driverfunc.

For example, the sampling hardware may not be able to do general
texelFetch() for some format/sample count combination, but the driver
may still be able to implement a reasonable resolve operation, so it can
be supported for renderbuffers.

V2: - Don't break Gallium compile.

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
mesa: helper for checking renderbuffer sample count

Pulls the checking of the sample count into a helper function, and
extends the existing logic to include the interactions with both
ARB_texture_multisample and ARB_internalformat_query.

_mesa_check_sample_count() checks a desired sample count against a
a combination of target/internalformat, and returns the error enum
to be produced, if any. Unfortunately the conditions are messy and the
errors vary.

V2: - Tidy up spurious block.
    - Move _mesa_check_sample_count() to multisample.c instead; It
      doesn't really belong in fbobject.c or teximage.c.
    - Inlined spec quotes

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
mesa: use _mesa_check_sample_count() for multisample textures

Extends _mesa_check_sample_count() to properly support the
TEXTURE_2D_MULTISAMPLE and TEXTURE_2D_MULTISAMPLE_ARRAY targets, which
have subtly different limits than renderbuffers.

This resolves the remaining TODO in the implementation of
TexImage*DMultisample.

V2: - Don't introduce spurious block.
    - Do this in multisample.c instead.
    - Fix typo in error message.
    - Inline spec quotes

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965: bump MAX_DEPTH_TEXTURE_SAMPLES to 4/8

Bump MAX_DEPTH_TEXTURE_SAMPLES to match what GetInternalformativ is
claiming. Since that limit is what is actually enforced now, this
doesn't actually change anything except the queried value.

There's still no piglits verifying that multisample depth textures work,
but this works in the Unigine demos.

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>