Make running soong_build in alternate modes nicer. am: a1b9372e am:...

Make running soong_build in alternate modes nicer. am: a1b9372e am: 815b9bab am: 31190856 am: 96804da7

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/1818332

Change-Id: I17b5520f4cfe18c14ff89c65fd24a7de9ff89faf