Fix zip_manifest_creator dep in bazel_tools repo with an alias.

In commit 78c19807d2cbb308b830022dcdcc8b03f19f90a9 I accidentally broke aar_import when I moved
zip_manifest_creator from tools/android to tools/zip because tools/android does
not have separate BUILD and BUILD.tools files. The test did not catch this,
because the dependency in tools/android/BUILD is correct in the context of the
bazel tree but not in the context of the bazel_tools embedded workspace.

--
MOS_MIGRATED_REVID=137209500
diff --git a/tools/android/BUILD b/tools/android/BUILD
index 74ddf95..b74a8ea 100644
--- a/tools/android/BUILD
+++ b/tools/android/BUILD
@@ -235,7 +235,7 @@
 sh_binary(
     name = "zip_manifest_creator",
     srcs = ["zip_manifest_creator.sh"],
-    data = ["//third_party/ijar:zipper"],
+    data = ["//tools/zip:zipper"],
 )
 
 sh_test(
diff --git a/tools/zip/BUILD b/tools/zip/BUILD
index 4c5ffe9..a7c996e 100644
--- a/tools/zip/BUILD
+++ b/tools/zip/BUILD
@@ -4,3 +4,8 @@
     name = "srcs",
     srcs = glob(["**"]),
 )
+
+alias(
+    name = "zipper",
+    actual = "//third_party/ijar:zipper",
+)