IPDEF5U [was Re: Simulating ZLE_RPROMPT_INDENT=0]

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

On Dec 19,  8:36pm, Peter Stephenson wrote:
}
} > ASIDE #2:  Having introduced IPDEF5U(), I wonder if there aren't some
} > of the other special variables that should have the PM_UNSET flag by
} > default.  OPTIND, OPTARG, and TRY_BLOCK_ERROR come to mind.
} 
} Yes, probably.

Fiddled with this a bit.  It's less trivial than it should be because
the code that manipulates the underlying C globals doesn't actually
set those variables, so if initialized to unset, they always appear so.
Unforutnately, this is probably not worth untangling.