Merge "Add tests for "unset" select statements" into main am: 767a1fe6

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/3016592



Change-Id: I60298949b6e41a7abc72b1048b89cd94726354d7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>