fix include style relating to cplusplus libraries

... and adjust INCLUDEPATH accordingly.

while i'm at messing with include statements, also re-order the include
blocks according to policy and sort them within bigger blocks.

Change-Id: I7762abfd7c4ecf59432b99db2f424e4fa25733a5
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/cpptools/cppqtstyleindenter.cpp

@@ -33,6 +33,7 @@
 #include "cpptoolssettings.h"
 #include "cppcodestylepreferences.h"
 #include "cpptoolsconstants.h"
+
 #include <texteditor/tabsettings.h>
 #include <texteditor/texteditorsettings.h>