elf: Update comments for check_relocs in elf_backend_data
Since
commit 5c3261b0e834647cf9eb555320e20871b7854f98
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Mon Oct 16 03:49:54 2017 -0700
ELF: Call check_relocs after opening all inputs
check_relocs is called after opening all inputs.
* elf-bfd.h (elf_backend_data::check_relocs): Update comments.