[C++] Rewrite of the preprocessor.

This rewrite fixes a couple of issues with the pre-processor. It now
supports:
- macros in macro bodies
- stringification of parameters [cpp.stringize]
- the concatenation operator [cpp.concat]
- #include MACRO_HERE
- defined() inside macro bodies used in pp-conditions.

Change-Id: Ifdb78041fb6afadf44f939a4bd66ce2832b8601f
Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>

src/libs/cplusplus/cplusplus.qbs

@@ -149,8 +149,8 @@ DynamicLibrary {
         "pp-cctype.h",
         "pp-engine.cpp",
         "pp-engine.h",
-        "pp-macro-expander.cpp",
-        "pp-macro-expander.h",
+        "PPToken.cpp",
+        "PPToken.h",
         "pp-scanner.cpp",
         "pp-scanner.h",
         "pp.h",