rtld: Return error if $ORIGIN for a dlopen-ed library cannot be resolved ...

instead of killing the process. The same behaviour of terminating
image activation if the $ORIGIN cannot be resolved for the main
object, is kept.

Reported by: Greg V <greg@unrelenting.technology>
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D23053