intel: Fix bpp setting of blits to 8bpp targets.

This was causing hangs in cairogears, as we would blit to the 8bpp target
(A8 texture) as 16bpp, and stomp over state objects.

src/mesa/drivers/dri/intel/intel_blit.c

@@ -332,6 +332,8 @@ intelEmitCopyBlit(struct intel_context *intel,
 
    switch (cpp) {
    case 1:
+      CMD = XY_SRC_COPY_BLT_CMD;
+      break;
    case 2:
    case 3:
       BR13 |= (1 << 24);