i965: Render R8G8B8X8 as R8G8B8A8

The sampler can handle R8G8B8X8 (and substitute 1.0 for the fourth
component) but we can't use it as a render target.

Signed-off-by: Chris Forbes <chrisf@ijw.co.nz>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Acked-by: Eric Anholt <eric@anholt.net>

src/mesa/drivers/dri/i965/brw_surface_formats.c

@@ -583,6 +583,9 @@ brw_init_surface_formats(struct brw_context *brw)
 	  */
 	 render = BRW_SURFACEFORMAT_B8G8R8A8_UNORM;
 	 break;
+      case BRW_SURFACEFORMAT_R8G8B8X8_UNORM:
+         render = BRW_SURFACEFORMAT_R8G8B8A8_UNORM;
+         break;
       }
 
       rinfo = &surface_formats[render];