Implement proper function pointer handling for validity checks #8646

Job	Run time
benchcomp-tests	4m 21s
perf	35m 12s
regression (macos-13)	46m 43s
write-json-symtab-regression	17m 18s
regression (ubuntu-20.04)	30m 0s
regression (ubuntu-22.04)	29m 19s
documentation	2m 9s
regression (macos-14)	29m 19s
	3h 14m 21s

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