.gitignore: ignore non-default build directories

4 jobs for cleanup/remove-autotools in 4 minutes and 2 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Test
passed dune:git--clang #9317

00:03:58

passed dune:git--gcc #9318

00:04:01

failed dune:git--clang #9315

00:01:06

failed dune:git--gcc #9316

00:01:02