minigbm: consistent style

- Sometimes were return -1 and sometimes -errno.  Prefer -errno
  wherever possible.
- No braces for single line if/else statements.  This does not
  apply gralloc3/gralloc4, since that directory follows AOSP
  style.

BUG=b:178495907
TEST=Cuttlefish CFI

Change-Id: I4c35768e015109730772a972b4b18e8d2c3cbb9b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/minigbm/+/2665001
Reviewed-by: Gurchetan Singh <[email protected]>
Reviewed-by: Jason Macnak <[email protected]>
Commit-Queue: Gurchetan Singh <[email protected]>
Tested-by: Gurchetan Singh <[email protected]>
13 files changed