Csh dumps core

[larry at ism780.UUCP]

...

4.2BSD csh (and possibly other csh's) dumps core on the following examples:

	% alias foo "eval `grep \!$ $HOME/.cshrc`"
and
	% alias bar foreach x '(\!\!*) \
	echo $x\:'
	% bar

both admittedly rather pathologic things.  But dumping core does not seem
to be a response in the realm of acceptability.

The first problem is that, upon recognizing that it about to do something
and is already in the middle of doing something, the dobackp() routine in
sh.glob.c calls abort().

The second problem is that the readc() routine in sh.lex.c tests

	if (*alvec)

when alvec==0.  I offer no suggested fixes as yet, but if anyone has seen
these problems before and has a fix, please post it.  Thanks.