MFC r274383:

Test errno against EEXIST as well.
Update the FreeBSD versions in the stable/10 errata file.

Approved by:	re (implicit)
Sponsored by:	The FreeBSD Foundation
Always return pathname in dl_iterate_phdr's dlpi_name, as Linux does

Linux LD_ITERATE_PHDR(3):
    The dlpi_name field is a null-terminated string giving the
    pathname from which the shared object was loaded.

That functionality is much more useful than returning just the short
name.

Update dl_iterate_phdr(3) to follow r272842

MFC of r272842 and r272848