Detect macros with duplicate metavariable bindings #11265

Job	Run time
build-and-check-gcc-5	36m 19s
build-and-check-ubuntu-32bit	40m 21s
build-and-check-ubuntu-64bit-glibcxx	35m 18s
build-and-check-ubuntu-64bit	26m 27s
build-and-check-asan	41m 43s
	3h 0m 8s

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