Rollup merge of #132577 - Urgau:check-cfg-report-extern-macro, r=petrochenkov

Report the `unexpected_cfgs` lint in external macros

This PR marks the `unexpected_cfgs` lint as being reportable in external macros, as it's probably not the intention of the macro author to leave ineffective cfgs in the users code.

Fixes #132572

try-job: aarch64-gnu-debug

Author: matthiaskrgr