Handle ARM triples without an endianness suffix
Handle ARM triples without an endianness suffix

Alpine seems to use this, and it results in a wrong
builtins.currentSystem. Big-endian ARM systems have triples starting
with armv6eb- or armv7eb-, so this doesn't change any systems that
already worked.

bennofs/nix,rycee/nix,rycee/nix,shlevy/nix,bennofs/nix,pikajude/nix,layus/nix,peti/nix,vcunat/nix,shlevy/nix,peti/nix,bennofs/nix,ehmry/nix,peti/nix,dezgeg/nix,layus/nix,zimbatm/nix,dezgeg/nix,zimbatm/nix,ehmry/nix,shlevy/nix,layus/nix,ysangkok/nix,ysangkok/nix,dtzWill/nix,zimbatm/nix,ehmry/nix,NixOS/nix,dezgeg/nix,ehmry/nix,dtzWill/nix,NixOS/nix,dezgeg/nix,pikajude/nix,dtzWill/nix,dtzWill/nix,vcunat/nix,ehmry/nix,rycee/nix,rycee/nix,ysangkok/nix,peti/nix,ehmry/nix,peti/nix,zimbatm/nix,layus/nix,vcunat/nix,layus/nix,bennofs/nix,shlevy/nix,NixOS/nix,shlevy/nix,rycee/nix,pikajude/nix,NixOS/nix,dtzWill/nix,vcunat/nix,NixOS/nix,dezgeg/nix