Update .clang-format to handle Objective-C files

Change-Id: I8686681ee9b96f0447f03a26e5568964ec5be6d9
Reviewed-on: https://skia-review.googlesource.com/144121
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
1 file changed