Update gccjit dependency and libgccjit commit #2920

Job	Run time
duplicates	4s
spell_check	7s
build_system	23s
build (gcc-15.deb, --extended-regex-example-tests)	7m 36s
build (gcc-15.deb, --projects)	11m 49s
build (gcc-15.deb, --std-tests)	6m 6s
build (gcc-15.deb, --extended-rand-tests)	8m 28s
build (gcc-15.deb, --test-libcore)	18m 10s
build (gcc-15-without-int128.deb, --std-tests)	6m 24s
build (gcc-15.deb, --test-successful-rustc --nb-parts 2 --current-part 1)	14m 14s
build (gcc-15-without-int128.deb, --test-libcore)	15m 36s
build (gcc-15-without-int128.deb, --extended-regex-example-tests)	7m 25s
build (gcc-15.deb, --test-successful-rustc --nb-parts 2 --current-part 0)	14m 50s
build (gcc-15-without-int128.deb, --extended-rand-tests)	8m 26s
build (gcc-15-without-int128.deb, --extended-regex-tests)	12m 20s
build (gcc-15-without-int128.deb, --test-successful-rustc --nb-parts 2 --current-part 1)	14m 10s
build (gcc-15.deb, --extended-regex-tests)	12m 0s
build (gcc-15-without-int128.deb, --projects)	11m 43s
build (gcc-15-without-int128.deb, --test-successful-rustc --nb-parts 2 --current-part 0)	14m 28s
success	3s
	3h 4m 22s

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