Test for overflow in eh_frame_hdr entries and for overlapping FDEs

Test for overflow in eh_frame_hdr entries and for overlapping FDEs

With larger binaries on 64-bit systems, or indeed just binaries that
have a large gap between text and data, it is possible for the
.eh_frame_hdr lookup table entry values to overflow a signed 32-bit
relative offset.  It is also a requirement for the glibc FDE lookup
code that only one FDE claim to cover any given address.

	* elf-bfd.h (struct eh_frame_array_ent): Add "range".
	* elf-eh-frame.c (_bfd_elf_write_section_eh_frame): Stash address
	range of FDEs to hdr_info->array.
	(_bfd_elf_write_section_eh_frame_hdr): Report overflow in
	.eh_frame_hdr entries, and overlapping FDEs.