fakevim: fix endless loop in certain search&replace operations

Task-number: QTCREATORBUG-5697
Change-Id: I25e9ef4ef042efa2b4dd670f5177e5e170fbaaf0
(cherry picked from commit d8fdd0acdc)
Reviewed-on: http://codereview.qt.nokia.com/2574
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Eike Ziller <eike.ziller@nokia.com>

src/plugins/fakevim/fakevimhandler.cpp

@@ -3226,7 +3226,7 @@ bool FakeVimHandler::Private::handleExSubstituteCommand(const ExCommand &cmd)
                 }
             }
             text = text.left(pos) + repl + text.mid(pos + matched.size());
-            pos += matched.size();
+            pos += repl.size();
             if (!global)
                 break;
         }