Remove backward-compatibility-0300 patch

BUG=b:340376465
TEST=emerge-volteer libchrome
TEST=CQ

Change-Id: If613a17b9a546e53a316a5ebf3115d366d0fbb82
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/libchrome/+/5543723
Commit-Queue: Nathan Muggli <nmuggli@google.com>
Reviewed-by: Grace Cham <hscham@chromium.org>
Tested-by: Byron Lee <byronlee@chromium.org>
1 file changed