lksctp-tools: add license

pkgs/os-specific/linux/lksctp-tools/default.nix

···
     sha256 = "05da6c2v3acc18ndvmkrag6x5lf914b7s0xkkr6wkvrbvd621sqs";
   };
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "Linux Kernel Stream Control Transmission Protocol Tools.";
     homepage = http://lksctp.sourceforge.net/;
-    platforms = stdenv.lib.platforms.linux;
+    license = with licenses; [ gpl2 lgpl21 ]; # library is lgpl21
+    platforms = platforms.linux;
   };
 }