address compile issue brought up by @cwsmith

jacobmerson · jacobmerson · commit 86b4cddf101a · 2018-08-08T11:13:32.000-04:00
diff --git a/apf/apfConvert.cc b/apf/apfConvert.cc
@@ -7,6 +7,7 @@
 #include "apfNumbering.h"
 #include <map>
 #include <pcu_util.h>
+#include <iostream>
 
 namespace apf {
 
