Both gcc and clang allow the use of '$' in their identifiers as an
extension. moc should not throw a parse error if there is one in the
file. Instead, consider '$' as valid in identifiers.
Task-number: QTBUG-22720
Change-Id: I8be3a52429c0db5b7e8308b8f4fe475d3d3994bf
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>