Enable run_memleaks ObjcConfiguration in Skylark.

--
MOS_MIGRATED_REVID=140356545
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcConfiguration.java
index 4d730fb..84fa4a5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcConfiguration.java
@@ -181,6 +181,11 @@
     return generateLinkmap;
   }
 
+  @SkylarkCallable(
+    name = "run_memleaks",
+    structField = true,
+    doc = "Returns a boolean indicating whether memleaks should be run during tests or not."
+  )
   public boolean runMemleaks() {
     return runMemleaks;
   }