__cxa_thread_call_dtors(3): fix dtor pointer validity check

When checking for the destructor pointer belonging to some still
loaded dso, do not limit the possible dso to the one instantiated the
destructor. For instance, dso could set up the dtr pointer to a function
from libcxx.

PR: 278701
Reported by: vd
Reviewed by: dim, emaste, markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D45074