Enabling BSD_CRTBEGIN on amd64 resulted in
error: unused variable '__CTOR_LIST__'.
__CTOR_LIST__ is indeed unused in crtbegin.c; it marks the beginning of
the .ctors array and is used in crtend.c. Annotate __DTOR_LIST__ as
well for consistency.
Discussed with: andrew
MFC with: r339738
Sponsored by: The FreeBSD Foundation
d7f804e35b