libtool wrapper script to isolate the unfortunate hacks we must make to get around apple's buggy libtool tool

--
MOS_MIGRATED_REVID=123024674
diff --git a/tools/objc/BUILD b/tools/objc/BUILD
index 1fa4628..149a9bb 100644
--- a/tools/objc/BUILD
+++ b/tools/objc/BUILD
@@ -64,6 +64,14 @@
 )
 
 sh_binary(
+    name = "libtool",
+    srcs = [":libtool.sh"],
+    data = [
+        ":xcrunwrapper",
+    ],
+)
+
+sh_binary(
     name = "actoolwrapper",
     srcs = [":actoolwrapper.sh"],
     data = [