Merge "Add targets for flex and m4" am: 424cdd9feb am: 2f62805664 am: 0c18fb2419 am: 26ddb42615

Original change: https://android-review.googlesource.com/c/platform/prebuilts/build-tools/+/2063031

Change-Id: I8121071240ee5c2ec5ce2f55b1577da6c8822d5c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>