Fix bug (and test) for an invocation using macro name as a non-macro argument

Fix bug (and test) for an invocation using macro name as a non-macro argument

This adds a second shift/reduce conflict to our grammar. It's basically the
same conflict we had previously, (deciding to shift a '(' after a FUNC_MACRO)
but this time in the "argument" context rather than the "content" context.

It would be nice to not have these, but I think they are unavoidable
(withotu a lot of pain at least) given the preprocessor specification.