Disable clippy's now-default swap-with-temporary buggy lint

This lint fires when we do a swap with a value stored in a mutex,
as it sees the `&mut x.lock().unwrap()` as a temporary which can be
taken from, even though it is in fact not.

Author: TheBlueMatt

ci/check-lint.sh

@@ -10,6 +10,7 @@ CLIPPY() {
 		`# Things where clippy is just wrong` \
 		-A clippy::unwrap-or-default \
 		-A clippy::upper_case_acronyms \
+		-A clippy::swap-with-temporary \
 		`# Things where we do odd stuff on purpose ` \
 		-A clippy::unusual_byte_groupings \
 		-A clippy::unit_arg \