Rollup merge of #149458 - GuillaumeGomez:clippy-cg_gcc, r=kobzol

Run clippy on cg_gcc in CI

This is to prevent [this issue](rust-lang/rust#149449 (comment)): in cg_gcc repository, we run clippy on our code but not in here, which can create issues.

cc ````@antoyo````
r? ````@Kobzol````

Author: matthiaskrgr