minigbm: Implemented cros_gralloc

It is desirable to have a gralloc implementation based on the same
drivers we use for minigbm. This will help synchronize the code between
CrOS and the Android container.

BUG=chromium:616275
TEST=Ran the gralloc unit test:

test_that -b veyron_minnie-cheets $IP1 graphics_Gralloc

Verified it succeeded.

CQ-DEPEND=CL:395066

Change-Id: Iff11eba3a92268327ef00eb12b4eabe6fc190cf3
Reviewed-on: https://chromium-review.googlesource.com/362062
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
diff --git a/drv_priv.h b/drv_priv.h
index 67376b9..09a8364 100644
--- a/drv_priv.h
+++ b/drv_priv.h
@@ -7,6 +7,7 @@
 #ifndef DRV_PRIV_H
 #define DRV_PRIV_H
 
+#include <pthread.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <sys/types.h>