Sort //gn/*.gni file lists.

Sorting all files in the *.gni file lists in //gn. This makes
them easier to compare with generated *.gni files which is in
an upcoming change.

Bug: skia:13485
Change-Id: I3384bc140aeaf79d4e20aab55bbcd3607607515a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/567296
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Chris Mumford <cmumford@google.com>
5 files changed