Currently, rustfmt requires to be enabled per repository. Add a comment
near the current project allowed_list as a reminder.
Test: None
Bug: 160223496
Change-Id: Iecf8d5b693620541a00d8ddc905549652025eed9
rust_library now produces only rlib and dylib variants.
rust_library_foreign now produces static and shared variants.
This change was made because both are common cases, but all four
together essentially never happens. This allows us to have fewer repeat
module definitions.
Bug: 143217452
Test: cd external/rust; mma
Change-Id: Iaf69e8da38f7c12710331c51464699cf7cbbb656