Rollup merge of #45135 - michaelwoerister:move-incr-comp-with-macro-export, r=alexcri...

incr.comp.: Move macro-export test case to src/test/incremental.

`compile-fail/incr_comp_with_macro_export.rs` was trying to role its own incremental compilation setup. This started to cause problems. There's no reason to not just make this a regular `src/test/incremental` test.

Fixes #45062.