Cleanup lto dead code #2926

Job	Run time
build_system	26s
duplicates	4s
spell_check	11s
build (gcc-15.deb, --extended-rand-tests)	8m 52s
build (gcc-15.deb, --std-tests)	5m 55s
build (gcc-15.deb, --test-libcore)	15m 21s
build (gcc-15.deb, --extended-regex-example-tests)	6m 9s
build (gcc-15-without-int128.deb, --test-successful-rustc --nb-parts 2 --current-part 1)	13m 9s
build (gcc-15-without-int128.deb, --extended-regex-example-tests)	7m 18s
build (gcc-15-without-int128.deb, --test-libcore)	16m 53s
build (gcc-15.deb, --extended-regex-tests)	11m 41s
build (gcc-15.deb, --test-successful-rustc --nb-parts 2 --current-part 0)	12m 44s
build (gcc-15.deb, --projects)	12m 32s
build (gcc-15.deb, --test-successful-rustc --nb-parts 2 --current-part 1)	13m 10s
build (gcc-15-without-int128.deb, --test-successful-rustc --nb-parts 2 --current-part 0)	12m 59s
build (gcc-15-without-int128.deb, --std-tests)	5m 54s
build (gcc-15-without-int128.deb, --projects)	11m 40s
build (gcc-15-without-int128.deb, --extended-rand-tests)	8m 57s
build (gcc-15-without-int128.deb, --extended-regex-tests)	12m 21s
success	4s
	2h 56m 20s

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