Merge branch 'master' into staging-next

There ver very many conflicts, basically all due to
name -> pname+version.  Fortunately, almost everything was auto-resolved
by kdiff3, and for now I just fixed up a couple evaluation problems,
as verified by the tarball job.  There might be some fallback to these
conflicts, but I believe it should be minimal.

Hydra nixpkgs: ?compare=1538299

pkgs/development/compilers/mosml/default.nix

@@ -6,7 +6,7 @@ stdenv.mkDerivation rec {
 
   buildInputs = [ gmp perl ];
 
-  makeFlags = "PREFIX=$(out)";
+  makeFlags = [ "PREFIX=$(out)" ] ++ stdenv.lib.optionals stdenv.isDarwin [ "CC=cc" ];
 
   src = fetchurl {
     url = "https://github.com/kfl/mosml/archive/ver-${version}.tar.gz";
@@ -23,7 +23,7 @@ stdenv.mkDerivation rec {
     '';
     homepage = https://mosml.org/;
     license = licenses.gpl2;
-    platforms = platforms.linux;
+    platforms = platforms.unix;
     maintainers = with maintainers; [ vaibhavsagar ];
   };
 }