CppEditor: Lower reservation of parentheses per line

Change-Id: Ibefa62dd30cc35d4eb1997484e28d91f1ab0288f
Task-number: QTCREATORBUG-14390
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@theqtcompany.com>

src/plugins/cppeditor/cpphighlighter.cpp

@@ -114,7 +114,7 @@ void CppHighlighter::highlightBlock(const QString &text)
     const unsigned firstNonSpace = tokens.first().utf16charsBegin();
 
     Parentheses parentheses;
-    parentheses.reserve(20); // assume wizard level ;-)
+    parentheses.reserve(5);
 
     bool expectPreprocessorKeyword = false;
     bool onlyHighlightComments = false;