[third_party/ffmpeg] stop renaming files, use newest Chromium commit

This CL fixes an issue with the roll process that was creating a bad
ffmpeg_generated.gni file. It also brings third_party/ffmpeg
up-to-date with respect to Chromium's ffmpeg repo. The new Chromium
commit is 5f4813ac6fded755ee386f94fbc5440748c09e71.

The roll process was doing some unnecessary renaming, which is used
in Chromium to ensure all source files have unique basenames. This is
evidently required for the mac build. Fuchsia has no such need.

Our roll process was doing some renames that had not been done in
Chromium, causing files to be referenced by names that don't appear
in the Chromium repo. This CL removes all the renaming code from
the generated_gn.py script, so all files are referenced by their
unmodified names.

Test: build issue
Change-Id: I8a9c6e4d67c03145666e36588c21205aca7ab659
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/ffmpeg/+/747862
Reviewed-by: Nathan Mulcahey <nmulcahey@google.com>
19 files changed