Merge "Handle -Cflag syntax and use prebuilt cargo." am: b517b4614d am: a321869ef5 am: 21480a98b1 am: 8cd4acaa36 am: 09cbf58bce

Original change: https://android-review.googlesource.com/c/platform/development/+/1371298

Change-Id: I3e400b21c5dd75ec50c44711d8477bcfa41d6d1d