st/dri: Add support for PIPE_FORMAT_RGBX8888_UNORM

The original dri2_format_to_pipe_format function just misses case branch
for __DRI_IMAGE_FORMAT_XBGR8888. I discovered this when debugging one google
map crash inside emulator.

Bug: b/37483848
Change-Id: I0e7b6e18308f6afb90bfd9ccaadfd3c0c604b2cf
Signed-off-by: Lepton Wu <lepton@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/540285
Reviewed-by: Chad Versace <chadversary@chromium.org>
diff --git a/src/gallium/state_trackers/dri/dri2.c b/src/gallium/state_trackers/dri/dri2.c
index 28f8078..69eec2e 100644
--- a/src/gallium/state_trackers/dri/dri2.c
+++ b/src/gallium/state_trackers/dri/dri2.c
@@ -134,6 +134,9 @@
    case __DRI_IMAGE_FORMAT_ARGB8888:
       pf = PIPE_FORMAT_BGRA8888_UNORM;
       break;
+   case __DRI_IMAGE_FORMAT_XBGR8888:
+      pf = PIPE_FORMAT_RGBX8888_UNORM;
+      break;
    case __DRI_IMAGE_FORMAT_ABGR8888:
       pf = PIPE_FORMAT_RGBA8888_UNORM;
       break;