Include memleaks plugin support for experimental_ios_test

--
MOS_MIGRATED_REVID=105876178
diff --git a/tools/objc/BUILD b/tools/objc/BUILD
index 46b0e47..897eac6e 100644
--- a/tools/objc/BUILD
+++ b/tools/objc/BUILD
@@ -46,6 +46,11 @@
     srcs = [":testrunner_stub"],
 )
 
+filegroup(
+    name = "memleaks_plugin",
+    srcs = [":memleaks_plugin_stub"],
+)
+
 sh_binary(
     name = "ibtoolwrapper",
     srcs = [":ibtoolwrapper.sh"],