gn format BUILD.gn

Change-Id: Ifd81cf84d0c9ea4ba7dbbec212961ebd7b18424c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/253361
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed