CppTools: set default -std=c++11 for Qt4

qmake from Qt4 does not provide C++ standard and
clang can't properly compile Qt4.8.6 and earlier
with c++1z. Behavior in this commit mimics qmake
from Qt5 which also provides c++11 as a default
standard.

Task-number: QTCREATORBUG-16441
Change-Id: I3d29891d6e47f2367f2b3b2bf4be4d86661924e9
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/cpptools/cppcodemodelinspectordumper.cpp

@@ -144,7 +144,8 @@ QString Utils::toString(ProjectPart::QtVersion qtVersion)
     switch (qtVersion) {
     CASE_QTVERSION(UnknownQt);
     CASE_QTVERSION(NoQt);
-    CASE_QTVERSION(Qt4);
+    CASE_QTVERSION(Qt4_8_6AndOlder);
+    CASE_QTVERSION(Qt4Latest);
     CASE_QTVERSION(Qt5);
     // no default to get a compiler warning if anything is added
     }