Fix/endianness #1393

Job	Run time
duplicates	4s
build (libgccjit.so, master, --mini-tests)	10m 42s
build (libgccjit.so, master, --std-tests)	10m 54s
build (libgccjit.so, master, --test-libcore)	23m 51s
build (libgccjit.so, master, --extended-rand-tests)	13m 59s
build (libgccjit.so, master, --extended-regex-example-tests)	13m 49s
build (libgccjit.so, master, --extended-regex-tests)	19m 41s
build (libgccjit.so, master, --test-successful-rustc --nb-parts 2 --current-part 0)	24m 10s
build (libgccjit.so, master, --test-successful-rustc --nb-parts 2 --current-part 1)	24m 38s
build (libgccjit_without_int128.so, master-without-128bit-integers, --mini-tests)	12m 36s
build (libgccjit_without_int128.so, master-without-128bit-integers, --std-tests)	12m 45s
build (libgccjit_without_int128.so, master-without-128bit-integers, --test-libcore)	25m 7s
build (libgccjit_without_int128.so, master-without-128bit-integers, --extended-rand-tests)	14m 6s
build (libgccjit_without_int128.so, master-without-128bit-integers, --extended-regex-example-tests)	12m 27s
build (libgccjit_without_int128.so, master-without-128bit-integers, --extended-regex-tests)	18m 0s
build (libgccjit_without_int128.so, master-without-128bit-integers, --test-successful-rustc --nb-...	24m 0s
build (libgccjit_without_int128.so, master-without-128bit-integers, --test-successful-rustc --nb-...	24m 54s
	4h 45m 43s

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