ath9k: fix build of old gmp by disabling compiler warnings (#408390)

    perl

  ];

  env.NIX_CFLAGS_COMPILE = "-w"; # old libiberty emits fatal warnings

  env.NIX_CFLAGS_COMPILE =

    # old libiberty emits fatal warnings

    "-w"

    # old gmp fails to compile with newer gcc

    # FIXME remove when the normal version has moved on

    + lib.optionalString (!enableUnstable) " -fpermissive";

  dontUseCmakeConfigure = true;

  enableParallelBuilding = true;