Bug 577921 mark DEBUG only variables as ifdef DEBUG in xpcom

r=bsmedberg
a=bsmedberg
a=sheriff for landing

xpcom/tests/TestArray.cpp

@@ -113,7 +113,10 @@ const char* AssertEqual(PRInt32 aValue1, PRInt32 aValue2)
 void DumpArray(nsISupportsArray* aArray, PRInt32 aExpectedCount, PRInt32 aElementIDs[], PRInt32 aExpectedTotal)
 {
   PRUint32 cnt = 0;
-  nsresult rv = aArray->Count(&cnt);
+#ifdef DEBUG
+  nsresult rv =
+#endif
+    aArray->Count(&cnt);
   NS_ASSERTION(NS_SUCCEEDED(rv), "Count failed");
   PRInt32 count = cnt;
   PRInt32 index;