removing this argument, and expanding when rc is NULL. This
effectively completes the back out of custom scripts for tftp booted
loaders from r269153 that was started in r292344 with the new path
tricks that obsoleted it.
Submitted by: Netflix
Don't print when we can't find a file. Copy it instead to the error
buffer. Higher level routines determine if it's appropriate to print
the error message.
Also, remove dead code (labeled bogusly lost functionality) since we
never used that functionality. Remove unused arg from interact() too.
Sponsored by: Netflix
