C++: Parse emit/Q_EMIT properly

The parser now understands emit/Q_EMIT as an expression statement.

Also, the recent fixes in the preprocessor introduced a side-effect
in the hanlding of code such as: emit signal(); Member signal started
being treated as a local use (parsed as a declaration) and possibily
being highlighted as unused variable.

Previously that worked by accident since there was an inconsistency
in the preprocessor on which only object-like macros were being
expanded even when the "no expand" flag was set. Then, the code
mentioned above was being parsed as an expression, what kind of worked.

Change-Id: I47a68ed4c1c1702872620b8ed7c7264fb0997034
Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>

src/libs/3rdparty/cplusplus/Token.h

@@ -217,7 +217,8 @@ enum Kind {
     T_FIRST_QT_KEYWORD,
 
     // Qt keywords
-    T_SIGNAL = T_FIRST_QT_KEYWORD,
+    T_EMIT = T_FIRST_QT_KEYWORD,
+    T_SIGNAL,
     T_SLOT,
     T_Q_SIGNAL,
     T_Q_SLOT,
@@ -230,6 +231,7 @@ enum Kind {
     T_Q_PROPERTY,
     T_Q_PRIVATE_PROPERTY,
     T_Q_INTERFACES,
+    T_Q_EMIT,
     T_Q_ENUMS,
     T_Q_FLAGS,
     T_Q_PRIVATE_SLOT,