Normaly, in C++ It's not valid to define a keyword, but it turns out that some
system header do, so we just silently accept it.
[ChangeLog][moc] moc no longer errors out if a C++ keyword is #define'ed
Task-number: QTBUG-61204
Change-Id: Ia4d3ff9c77b6ff261b6140c220cfb81bd13f1d6d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>