Merge "Flag an error on empty rust module srcs" am: 6ec96b8102 am: 2e2fb66ecc am: fdf99b1a08

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/1852788

Change-Id: Id5601ccffc34d303b88236311405452aacd93c0a