[lib] Fix infinite recursion for errors on vtys with terminal monitor enabled

[lib] Fix infinite recursion for errors on vtys with terminal monitor enabled

2006-07-10 Andrew J. Schorr <ajschorr@alumni.princeton.edu>

	* vty.c: (vty_log_out, vty_read, vty_flush, vtysh_flush, vtysh_read)
	  After an I/O error, must set vty->monitor to 0 before calling
	  zlog_warn, otherwise an infinite recursion could occur
	  (since zlog_warn triggers a message to be written to the vty,
	  and that in turn triggers another error message when it fails, etc.).