better common debug info

[craig@jcb-sc.com]

>Actually, the -fdebug-kludge option isn't really the place to "fix"
>debugging.  That code should go away.

This was unclear on my part: I meant it should go away once we fix
the "COMMON/EQUIVALENCE -g problem" in g77.  -fdebug-kludge is a
"short-term" (ha) kludge to work around that problem, and should
not be supported the moment we think we've fixed -g generally.

        tq vm, (burley)