minigbm: add clang-format and presubmit hooks

minigbm: add clang-format and presubmit hooks

Running the presubmit.sh script will apply our rules to every file in
the repo. Exclude gbm.h from the formatting requirements since this file
was taken from other open-source projects, and diffing will be easier
without our formatting rules.

In addition, special case drivers where the order of includes matters.

BUG=none
TEST=Verified the following commands succeed:

emerge-cyan minigbm/arc-cros-gralloc
emerge-oak minigbm/arc-cros-gralloc
emerge-veyron_minnie-cheets minigbm/arc-cros-gralloc
emerge-peach_pi minigbm
emerge-nyan_big minigbm
emerge-jadeite minigbm

Change-Id: I6ce93fb1930da254d13d5017766c17341870ccc9
Reviewed-on: https://chromium-review.googlesource.com/447319
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>