prebuilt android tools: Init using SDK

Expose as an option for the cross stdenv.

pkgs/development/mobile/androidenv/default.nix

@@ -242,4 +242,19 @@ rec {
     inherit (pkgs) stdenv;
     inherit androidsdk;
   };
+
+  androidndkPkgs = import ./androidndk-pkgs.nix {
+    inherit (buildPackages)
+      makeWrapper;
+    inherit (pkgs)
+      lib hostPlatform targetPlatform
+      runCommand wrapBintoolsWith wrapCCWith;
+    # buildPackages.foo rather than buildPackages.buildPackages.foo would work,
+    # but for splicing messing up on infinite recursion for the variants we
+    # *dont't* use. Using this workaround, but also making a test to ensure
+    # these two really are the same.
+    buildAndroidndk = buildPackages.buildPackages.androidenv.androidndk;
+    inherit androidndk;
+    targetAndroidndkPkgs = targetPackages.androidenv.androidndkPkgs;
+  };
 }