ld -r abort in _bfd_elf_write_section_eh_frame

ld -r abort in _bfd_elf_write_section_eh_frame

Turning on .eh_frame processing for ld -r resulted in systemtap
tickling a ld bug.  Triggered by the zero terminator not being added
to .eh_frame in a separate file as it usually is (crtend.o), but
instead being present in the last .eh_frame section along with CIEs
and FDEs.  The 4-byte terminator makes the section size check fail
on 64-bit targets.

	* elf-eh-frame (_bfd_elf_write_section_eh_frame): Adjust section
	size check to account for possible zero terminator.