MFC r257811 (by markj):
Include rtld itself when iterating over loaded ELF objects in
dl_iterate_phdr(3).

MFC r294373:
Do not call callbacks for dl_iterate_phdr(3) with the rtld bind and
phdr locks locked.

MFC r294470 (by kan):
Fix initlist_add_object invocation parameters.

MFC r294936 (by kan):
Do not unlock rtld_phdr_lock over callback invocations.