GPR #453: also fix asmcomp/arm64
GPR #453: also fix asmcomp/arm64

Commit abc5360dc15bfcafe3353ea352216bcdf7d8eea8 broke arm64;
this fixes it by mirroring the arm change.

msprotz/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,msprotz/ocaml,gerdstolpmann/ocaml,msprotz/ocaml