mlton: use callPackage

(cherry picked from commit ad0d43e)

pkgs/development/compilers/mlton/default.nix

@@ -1,26 +1,21 @@
-{ stdenv, fetchurl, fetchgit, patchelf, gmp, which }:
+{ callPackage }:
+
 rec {
-  mlton20130715 = import ./20130715.nix {
-    inherit stdenv fetchurl patchelf gmp;
-  };
+  mlton20130715 = callPackage ./20130715.nix {};
 
-  mlton20180207Binary = import ./20180207-binary.nix {
-    inherit stdenv fetchurl patchelf gmp;
-  };
+  mlton20180207Binary = callPackage ./20180207-binary.nix {};
 
-  mlton20180207 = import ./from-git-source.nix {
+  mlton20180207 = callPackage ./from-git-source.nix {
     mltonBootstrap = mlton20180207Binary;
     version = "20180207";
     rev = "on-20180207-release";
     sha256 = "00rdd2di5x1dzac64il9z05m3fdzicjd3226wwjyynv631jj3q2a";
-    inherit stdenv fetchgit gmp which;
   };
 
-  mltonHEAD = import ./from-git-source.nix {
+  mltonHEAD = callPackage ./from-git-source.nix {
     mltonBootstrap = mlton20180207Binary;
     version = "HEAD";
     rev = "e149c9917cfbfe6aba5c986a958ed76d5cc6cfde";
     sha256 = "0a0j1i0f0fxw2my1309srq5j3vz0kawrrln01gxms2m5hy5dl50d";
-    inherit stdenv fetchgit gmp which;
   };
 }