Fix structopt-derive/METADATA am: 7a5d9b3390 am: f7af03948a am: 51e0ea6cd3

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/structopt-derive/+/1414006

Change-Id: Ieecbffe821facfb44b8279045a45e363c83674ca