Add native CI for Aarch64 #1262

Job	Run time
build (libgccjit.so, master)	3m 26s
build (libgccjit_without_int128.so, master-without-128bit-integers)	2m 17s
build (libgccjit12.so, gcc12, --no-default-features, TEST_FLAGS='-Cpanic=abort -Zpanic-abort-test...	3m 2s
success_failures	2s
	8m 47s

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