Merge "Enable referencing of aapt-generated proguard flags" am: 7fecde90

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/2516696



Change-Id: I1de940d7b3bfadc5dbb9756941681f6bff70b2c2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>