preprocessor: do not loop endlessly on incomplete expressions

An missing closing parantheses after "defined(..." caused an endless loop.

Change-Id: I19b17cebc1a56880216c3bfb67c9d296f80cc064
Reviewed-by: Leandro Melo <leandro.melo@nokia.com>

src/libs/cplusplus/pp-engine.cpp

@@ -654,12 +654,12 @@ void Preprocessor::handleDefined(PPToken *tk)
             break;
     } while (isValidToken(*tk));
 
-    if (lparenSeen) {
-        while (tk->isNot(T_RPAREN))
-            lex(tk);
-    } else {
-        pushToken(tk);
-    }
+
+    if (lparenSeen && tk->is(T_RPAREN))
+        lex(tk);
+
+    pushToken(tk);
+
     QByteArray result(1, '0');
     if (m_env->resolve(idToken.asByteArrayRef()))
         result[0] = '1';