GNU GMP upstream tip: ab4a7408e2ce

Official upstream K&R definitions present: 2

Unpatched:
Clang GNU23 configure: FAIL reproduced

Validated patch:
GCC GNU23 configure/build/make check: PASS
Clang GNU23 configure/build/make check: PASS
True test failures: 0
Non-regression: PASS

Patch scope:
acinclude.m4 only

Finding commit:
60de53223aab7cbdc34208ce7c5484a1903cc268

Validated fix commit:
e4dbdd2f5b203f77e2bcac62130af4b41d8bd98a

Backlink commit:
31fbcd2c8b3acb3aaeaf1ee4eb7a8575ee944296
