Merge "cargo2rulesmk.py: Support customizing rustc" into main am: a3f72f8382

Original change: https://android-review.googlesource.com/c/platform/development/+/2726754

Change-Id: I97bc24abedd6fb9bb4cfc51fe09de053f7c19700
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>