Introduce mock codepages config option for mtools am: 32c51e05eb am: ea3799d954

Original change: https://android-review.googlesource.com/c/platform/external/mtools/+/2307102

Change-Id: Ib9f256c8b2a6d40b80bddce45bd275d685bb36d8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>