Add support for fmaf16 #2410

Job	Run time
duplicates	4s
build_system	24s
build (gcc-13.deb, --std-tests)	5m 36s
build (gcc-13.deb, --test-libcore)	13m 48s
build (gcc-13.deb, --extended-rand-tests)	8m 25s
build (gcc-13.deb, --extended-regex-example-tests)	6m 21s
build (gcc-13.deb, --extended-regex-tests)	10m 56s
build (gcc-13.deb, --test-successful-rustc --nb-parts 2 --current-part 0)	11m 13s
build (gcc-13.deb, --test-successful-rustc --nb-parts 2 --current-part 1)	10m 47s
build (gcc-13.deb, --projects)	11m 19s
build (gcc-13-without-int128.deb, --std-tests)	5m 51s
build (gcc-13-without-int128.deb, --test-libcore)	14m 38s
build (gcc-13-without-int128.deb, --extended-rand-tests)	8m 31s
build (gcc-13-without-int128.deb, --extended-regex-example-tests)	6m 45s
build (gcc-13-without-int128.deb, --extended-regex-tests)	12m 4s
build (gcc-13-without-int128.deb, --test-successful-rustc --nb-parts 2 --current-part 0)	11m 7s
build (gcc-13-without-int128.deb, --test-successful-rustc --nb-parts 2 --current-part 1)	11m 38s
build (gcc-13-without-int128.deb, --projects)	10m 56s
	2h 40m 23s

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