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/Parser.cpp

@@ -2947,6 +2947,23 @@ bool Parser::parseStatement(StatementAST *&node)
         node = ast;
     } return true;
 
+    case T_EMIT:
+    case T_Q_EMIT: {
+        // Simply skip the emit token and parse as an expression statement - no strong
+        // reason to have an specific ast type.
+        consumeToken();
+        ExpressionAST *expression = 0;
+        if (parsePostfixExpression(expression)) {
+            ExpressionStatementAST *ast = new (_pool) ExpressionStatementAST;
+            ast->expression = expression;
+            match(T_SEMICOLON, &ast->semicolon_token);
+            node = ast;
+            return true;
+        }
+        error(cursor(), "expected statement");
+        return false;
+    }
+
     default:
         if (LA() == T_IDENTIFIER && LA(2) == T_COLON)
             return parseLabeledStatement(node);