i965: Add comment to explain the weird-looking shadow compares.

This always looks crazy when I stumble across it, until I remember
what the hardware is doing. Describing it ought to short-circuit
that process next time :)

V2: Fix indents to 6 spaces, not 7.

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
i965: glClearBuffer() should only clear a single buffer.

glClearBuffer() is currently clearing all active draw color buffers (all
buffers that have not been set to GL_NONE when calling glDrawBuffers) instead
of only clearing the one it receives as parameter. Altough brw_clear()
receives a bit mask indicating the color buffers that should be cleared,
this mask is ignored when calling brw_blorp_clear_color().

This was breaking the 'fbo-drawbuffers-none glClearBuffer' piglit test.

The patch provides the bit mask to brw_blorp_clear_color() so it can limit
clearing to the color buffers present in the mask.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76832
Reviewed-by: Eric Anholt <eric@anholt.net>
mesa: Fix typo in error message

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
egl-static: fix build after recent radeon winsys changes

Signed-off-by: Marek Olšák <marek.olsak@amd.com>