Normally, modern unwinders uses Dwarf information to unwind stack,
however in case when the code is not annotated by Dwarf instructions,
unwinders fallbacks to a frame-pointer based algorithm.
That is allows libunwind to unwind stack from global constructors and
destructors. Also it makes gdb happy as it printed nonexistent frame
before.
Reviewed by: kib, imp
Differential Revision: https://reviews.freebsd.org/D40948
This was a leftover from when we had both i386 a.out and ELF.
Reviewed by: kib, imp
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D2591