xtensa: bfd: fix assertion in xlate_offset_with_removed_text

xtensa: bfd: fix assertion in xlate_offset_with_removed_text

Linking objects containing jumps targeting the end of a section triggers
assertion in the xlate_offset_with_removed_text. Such jumps may be
generated by a compiler as a dead code and not removed at -O0. Allow
such jumps.
While at it make bsearch argument match comparison function expectations
and use bfd_vma for address fields in the struct xlate_map_entry.

bfd/
2018-03-15  Max Filippov  <jcmvbkbc@gmail.com>

	* elf32-xtensa.c (xlate_map_entry): Change types of address
	fields from 'unsigned' to 'bfd_vma'.
	(xlate_offset_with_removed_text): Use struct xlate_map_entry as
	the key argument to bsearch. Allow offsets past the end of a
	section, use the last map entry for translation of such offsets.