Catch exceptions by const reference.

Change-Id: Ic537fd123478a4f8fe4e54736d444fa64fd62d9c
Reviewed-by: hjk <hjk121@nokiamail.com>

src/libs/utils/portlist.cpp

@@ -63,7 +63,7 @@ public:
         try {
             if (!atEnd())
                 parseElemList();
-        } catch (ParseException &e) {
+        } catch (const ParseException &e) {
             qWarning("Malformed ports specification: %s", e.error);
         }
         return m_portList;