Get android path from env (fixes #746)

--
Change-Id: Ideb2011d23da470276420afcc8b5a71f1470f391
Reviewed-on: https://bazel-review.googlesource.com/#/c/2771
MOS_MIGRATED_REVID=113639747
diff --git a/.gitignore b/.gitignore
index fa433ac..95270e9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@
 /.idea/
 /.project
 /.settings
+/WORKSPACE.user.bzl
 /base_workspace/*
 /bazel-bazel
 /bazel-bin