Clean up rust_test_host TEST_MAPPING after default update

After b/177689340, rust_test_host doesn't need TEST_MAPPING config anymore to run in
presubmit.

Change-Id: I49a50ae9b7ea2125588b99100df6b3af20619604
Test: presubmit
Bug: 178646865
1 file changed
tree: c49f24dc45c93c3133f65c704a96a2dd85910665
  1. benches/
  2. out/
  3. patches/
  4. src/
  5. .cargo_vcs_info.json
  6. Android.bp
  7. build.rs
  8. Cargo.toml
  9. Cargo.toml.orig
  10. LICENSE.txt
  11. METADATA
  12. MODULE_LICENSE_MIT
  13. OWNERS
  14. README.md
  15. regenerate.sh
README.md

How to develop rust-protobuf itself

cargo test --all to build everything.

If code generator is changed, code needs to be regenerated, see regenerate.sh.