test x clippy --stage 1 in ci

Author: jyn514

src/ci/docker/host-x86_64/x86_64-gnu-llvm-15/script.sh

@@ -47,3 +47,7 @@ fi
 # This is intended to make sure that both `--pass=check` continues to
 # work.
 ../x.ps1 --stage 2 test tests/ui --pass=check --host='' --target=i686-unknown-linux-gnu
+
+# Run clippy just to make sure it doesn't error out; we don't actually want to gate on the warnings
+# though.
+../x.py --stage 1 clippy -Awarnings