android: fix build with media_use_ffmpeg=false

When using `media_use_ffmpeg=false` in Android, some needed files were
being excluded, while others that use ffmpeg were being included.

Change-Id: I9014d691a07568ddb4fe32114dcbde0174c6bd0d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6372722
Reviewed-by: Mike West <mkwst@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Mark Foltz <mfoltz@chromium.org>
Commit-Queue: Henrique Ferreiro <hferreiro@igalia.com>
Cr-Commit-Position: refs/heads/main@{#1435782}