abitidy: improve usage message am: dfe849b6f6 am: c90bd45719 am: 1ab04669b8 am: aaac7befd6

Original change: https://android-review.googlesource.com/c/platform/external/libabigail/+/1996591

Change-Id: Id34503f4ae2bc725aeb20a405156f7f896b7ea48