mlton: change license to smlnj

pkgs/development/compilers/mlton/20130715.nix

@@ -131,5 +131,5 @@ stdenv.mkDerivation rec {
     cp -r $(pwd)/install/${usr_prefix}/man $out
   '';
 
-  meta = import ./meta.nix;
+  meta = import ./meta.nix { inherit lib; };
 }

pkgs/development/compilers/mlton/20180207-binary.nix

@@ -64,5 +64,5 @@ stdenv.mkDerivation rec {
       done
     '';
 
-  meta = import ./meta.nix;
+  meta = import ./meta.nix { inherit lib; };
 }

pkgs/development/compilers/mlton/20210117-binary.nix

@@ -84,5 +84,5 @@ stdenv.mkDerivation rec {
       done
     '';
 
-  meta = import ./meta.nix;
+  meta = import ./meta.nix { inherit lib; };
 }

pkgs/development/compilers/mlton/from-git-source.nix

@@ -1,4 +1,5 @@
 {
+  lib,
   fetchgit,
   gmp,
   mltonBootstrap,
@@ -45,5 +46,5 @@ stdenv.mkDerivation {
 
   doCheck = true;
 
-  meta = import ./meta.nix;
+  meta = import ./meta.nix { inherit lib; };
 }

pkgs/development/compilers/mlton/meta.nix

@@ -1,3 +1,6 @@
+{
+  lib,
+}:
 {
   description = "Open-source, whole-program, optimizing Standard ML compiler";
   longDescription = ''
@@ -10,7 +13,7 @@
   '';
 
   homepage = "http://mlton.org/";
-  license = "bsd";
+  license = lib.licenses.smlnj;
   platforms = [
     "i686-linux"
     "x86_64-linux"