Add METADATA / Licensing info am: 9d3a11dc81 am: 89eee9f7cb am: 84701a5b7d am: 474b3cfd3a

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/proc-macro-error-attr/+/1322600

Change-Id: Idedd9f6741ad9958317c4064f1730714a1ddb251