debugger: more robust Qt 4 vs Qt 5 detection in dumper

Change-Id: I2a1eb5181e614899f3cd80e0eaec5be9a3e93c77
Reviewed-by: hjk <qthjk@ovi.com>
(cherry picked from commit f626168c62)
Reviewed-by: Eike Ziller <eike.ziller@nokia.com>

share/qtcreator/dumper/dumper.py

@@ -587,8 +587,11 @@ def qtMajorVersion():
         return qqMajorVersion
     try:
         # -- Result is returned as character, need to subtract '0'
-        qqMajorVersion = int(parseAndEvaluate(qtNamespace() + "qVersion()[0]")) - 48
-        return qqMajorVersion
+        v = int(parseAndEvaluate("*(char*)qVersion()"))
+        if v >= 51:
+            qqMajorVersion = v - 48
+            return qqMajorVersion
+        return 0
     except:
         return 0