Fix empty rules and remove useless rules. Builds with error=all now.
Fix empty rules and remove useless rules. Builds with error=all now.

bleibig/rust-grammar,bleibig/rust-grammar,patperry/rust-grammar,patperry/rust-grammar,bleibig/rust-grammar,patperry/rust-grammar,patperry/rust-grammar,bleibig/rust-grammar