Add code to enable USE_BAZEL=1 m functionality in AOSP.

Test: Manually, but builds currently fail due to a recent change to bazel_handler.go.
Change-Id: I9a45a2c73d1755032b11f6b913c03f83a28f63c5
diff --git a/ui/build/Android.bp b/ui/build/Android.bp
index 4ef2721..c314b7b 100644
--- a/ui/build/Android.bp
+++ b/ui/build/Android.bp
@@ -39,6 +39,7 @@
         "blueprint-microfactory",
     ],
     srcs: [
+        "bazel.go",
         "build.go",
         "cleanbuild.go",
         "config.go",