main: check texture target when validating layered framebuffers.

From section 4.4.4 (Framebuffer Completeness) of the GL 3.2 spec:

    If any framebuffer attachment is layered, all populated
    attachments must be layered. Additionally, all populated color
    attachments must be from textures of the same target.

We weren't checking that the attachments were from textures of the
same target.

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>
i965: Fix clears of layered framebuffers with mismatched layer counts.

Previously, Mesa enforced the following rule (from
ARB_geometry_shader4's list of criteria for framebuffer completeness):

  * If any framebuffer attachment is layered, all attachments must have
    the same layer count.  For three-dimensional textures, the layer count
    is the depth of the attached volume.  For cube map textures, the layer
    count is always six.  For one- and two-dimensional array textures, the
    layer count is simply the number of layers in the array texture.
    { FRAMEBUFFER_INCOMPLETE_LAYER_COUNT_ARB }

However, when ARB_geometry_shader4 was adopted into GL 3.2, this rule
was dropped; GL 3.2 permits different attachments to have different
layer counts.  This patch brings Mesa in line with GL 3.2.

In order to ensure that layered clears properly clear all layers, we
now have to keep track of the maximum number of layers in a layered
framebuffer.

Fixes the following piglit tests in spec/!OpenGL 3.2/layered-rendering:
- clear-color-all-types 1d_array mipmapped
- clear-color-all-types 1d_array single_level
- clear-color-mismatched-layer-count
- framebuffer-layer-count-mismatch

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>
i965: Delete duplicate write_timestamp function.

brw_queryobj.c needs a version of write_timestamp that works on all
generations for the QueryCounter() driver hook.  So there's no point in
duplicating it in gen6_queryobj.c.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Eric Anholt <eric@anholt.net>
mesa: Set the correct error in _mesa_BeginConditionalRender

Piglit was recently changed to expect the correct error code (piglit
commit 271b998), so it started failing on Mesa.  This corrects that
failing and adds some spec quotations to justify the errrors set.

The code was rearranged a little bit to match the order listed in the
spec.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>