This CL adds the android_binary rule to Bazel. 

Note that despite the rule being present, Android support is still not functional: two tools (//tools/android:{aar_generator,resources_processor} are still missing (and are a-coming!)

--
MOS_MIGRATED_REVID=96099045
diff --git a/tools/BUILD b/tools/BUILD
index 39af650..6bd88fd 100644
--- a/tools/BUILD
+++ b/tools/BUILD
@@ -7,6 +7,7 @@
 filegroup(
     name = "srcs",
     srcs = glob(["**"]) + [
+        "//tools/android:srcs",
         "//tools/jdk:srcs",
         "//tools/genrule:srcs",
         "//tools/cpp:srcs",
diff --git a/tools/android/BUILD b/tools/android/BUILD
index de5114b..8c1e135 100644
--- a/tools/android/BUILD
+++ b/tools/android/BUILD
@@ -131,3 +131,8 @@
         ":stubify_manifest",
     ],
 )
+
+filegroup(
+    name = "srcs",
+    srcs = glob(["**"]),
+)