memcached: disable treating warnings as errors on darwin

PIE hardening is not available on darwin but it's just a warning.

+2
+2
pkgs/servers/memcached/default.nix
··· 12 12 13 13 hardeningEnable = [ "pie" ]; 14 14 15 + NIX_CFLAGS_COMPILE = stdenv.lib.optionalString stdenv.isDarwin "-Wno-error"; 16 + 15 17 meta = with stdenv.lib; { 16 18 description = "A distributed memory object caching system"; 17 19 repositories.git = https://github.com/memcached/memcached.git;