Return full pathname in dl_iterate_phdr's dlpi_name, as Linux does

[emaste]

Summary

Linux man page currently states

The dlpi_name field is a null-terminated string giving the pathname from which the shared object was loaded.

It may be that they returned just the name when this was first implemented for FreeBSD.

[emaste]

A use case in http://reviews.llvm.org/D5610

[emaste]

Looks like musl libc had the same discovery: http://www.openwall.com/lists/musl/2012/10/11/10

[emaste]

http://linux.die.net/man/3/dl_iterate_phdr

[emaste]

Committed in r272842