Add android_sdk to third_party to be used by golem when benchmarking

Right now the runners cannot build the target because they are missing
the android sdk.

Change-Id: I5d8ba65e1b1090628957c7285dc26edb2bd69e67
diff --git a/tools/apk_utils.py b/tools/apk_utils.py
index 41c80c2..86f1fe8 100644
--- a/tools/apk_utils.py
+++ b/tools/apk_utils.py
@@ -26,7 +26,7 @@
 def sign_with_apksigner(
     unsigned_apk, signed_apk, keystore, password='android', quiet=False):
   cmd = [
-    os.path.join(utils.ANDROID_BUILD_TOOLS, 'apksigner'),
+    os.path.join(utils.getAndroidBuildTools(), 'apksigner'),
     'sign',
     '-v',
     '--ks', keystore,