mesa: Skip clearing color buffers when color writes are disabled.

WebGL Aquarium in Chrome 24 actually hits this.

v2: Move to core Mesa (wisely suggested by Ian); only consider
    components which actually exist.

v3: Use _mesa_format_has_color_component to determine whether components
    actually exist, fixing alpha format handling.

v4: Add a comment, as requested by Brian.  No actual code changes.

Signed-off-by: Kenneth Graunke <[email protected]>
Reviewed-by: Brian Paul <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>
Tested-by: Dylan Baker <[email protected]>

0 files changed, 0 insertions, 0 deletions