treewide: Add lots of platforms to packages with no meta

Build-tested on x86_64 Linux and on Darwin.

pkgs/development/mobile/androidenv/androidndk.nix

@@ -77,4 +77,8 @@ stdenv.mkDerivation rec {
         wrapProgram "${bin_path}/$i" --prefix PATH : "${runtime_paths}"
     done
   '';
+
+    meta = {
+        platforms = stdenv.lib.platforms.linux;
+    };
 }

pkgs/development/mobile/androidenv/androidsdk.nix

@@ -232,4 +232,8 @@ stdenv.mkDerivation rec {
   '';
   
   buildInputs = [ unzip makeWrapper ];
+
+  meta = {
+    platforms = stdenv.lib.platforms.unix;
+  };
 }