Merge changes from topic "export-vars" am: a2a7b579 am: 066a777c am: fefe3547

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2044966



Change-Id: I3f71b23b335baa61b0b997e454d900a8e914c549
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>