cleanup code in the signal part of the event library
* Only attempt to forward standard input if we have a controlling terminal
(isatty() returns 1) and we are the foreground process OR we do not have
a controlling terminal (isatty() returns 0). If we have a controlling
terminal, check at each SIGCONT if we should change our forwarding,
since our foreground / background status may have changed.
Unfortunately, there isn't a great way in the iof framework to know if
we are capturing a starter's stdin. Use the logic that if it's a source
AND tagged as standard input, it's a starter's stdin. This seems to
work for all the common usages.
Both these need to go to the v1.0 branch.
This commit was SVN r8894.
03f6a8529c