Add android_sdk_repo_host to build platform-tools&build-tools

The Android SDK has been built with Make up until now, monolithically,
then split up into several sdk-repo zip files for different purposes.
The Mac and Windows SDKs really only need to contain the platform-tools
and build-tools pieces, but due to this monolithic sdk zip, we had to
build the whole SDK first.

This adds an `android_sdk_repo_host` module that can build these
platform-tools and build-tools zips.

Bug: 187222815
Change-Id: I55809e1d7447dd65e22461f921b2b8abb6d5f822
diff --git a/Android.bp b/Android.bp
index d6260b4..b5ddaa4 100644
--- a/Android.bp
+++ b/Android.bp
@@ -62,6 +62,7 @@
         },
     },
     notice: ":mingw-libwinpthread-notice",
+    licenses: ["winpthreads_license"],
 }
 
 kernel_headers {