CppTools: Do not append '/' to fallback header paths

...since this will confuse the completer.

Task-number: QTCREATORBUG-13567
Change-Id: I4172d433f23f3907690d4c00f92fadb68fa354e8
Reviewed-by: Erik Verbruggen <erik.verbruggen@theqtcompany.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>
CppEditor: Fix comment continuation

Do not continue a comment with '*' for

	*foo //<Enter>

and

	*foo /*<Enter>

Task-number: QTCREATORBUG-13415
Change-Id: I0bf062fb96942930f8c9a268bff832de219c7787
Reviewed-by: Erik Verbruggen <erik.verbruggen@theqtcompany.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>