binutils: enable gold when cross compiling on darwin

This basically reverts:
 - 3c5188cc ('binutils: disable gold when building on darwin')
 - 457b48cc ('binutils: apply patch when cross compiling from darwin')

Tested by building:
 - nix build -f . pkgsCross.i686-embedded.buildPackages.binutils
 - nix build -f . pkgsCross.aarch64-embedded.buildPackages.binutils

pkgs/development/tools/misc/binutils/default.nix

@@ -4,7 +4,7 @@
 , withAllTargets ? false, libbfd, libopcodes
 , enableShared ? !stdenv.hostPlatform.isStatic
 , noSysDirs
-, gold ? !stdenv.buildPlatform.isDarwin || stdenv.hostPlatform == stdenv.targetPlatform
+, gold ? true
 , bison ? null
 , flex
 , texinfo