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/libs/cplusplus/pp-engine.cpp

@@ -49,11 +49,10 @@
 #include "pp.h"
 #include "pp-cctype.h"
 
-#include <Control.h>
-#include <Lexer.h>
-#include <Token.h>
-#include <Literals.h>
-#include <cctype>
+#include <cplusplus/Control.h>
+#include <cplusplus/Lexer.h>
+#include <cplusplus/Token.h>
+#include <cplusplus/Literals.h>
 
 #include <QDebug>
 #include <QList>
@@ -61,6 +60,7 @@
 #include <QTime>
 #include <QPair>
 
+#include <cctype>
 #include <list>
 #include <algorithm>