cmArgumentParser: Ignore positional after keyword

Tweak cmArgumentParser to ignore positional arguments once a keyword
argument has been seen. This prevents mingling of keyword arguments
being able to effectively skip positional arguments, with later
arguments being picked up again; this seems highly likely to lead to
user confusion. This is also consistent with how other languages (e.g.
Python) handle a mix of "named" and positional arguments.
3 files changed