objdump.c: Fix coding for DISASSEMBLER_NEEDS_RELOC:

objdump.c: Fix coding for DISASSEMBLER_NEEDS_RELOC:
(struct objdump_disasm_info): Add 'reloc' field.
(disassemble_bytes): Fix check for when an insn has a reloc associated with it.
Improve comment explaining why the use of octets is wrong.  Set the 'reloc'
field in objdump_disasm_info structure.
(objdump_print_addr): Use new 'reloc' field to lookup the correct address for
the symbol associated with the current instruction's relocation.
(disassemble_info): Initialise 'reloc' field.

gas/arm/inst.d: Allow for ARM ports which decode the reloc associated with
branches and so show the exact symbolic destination address rather than an
offset from the start of the section.

gas/arm/pic.d: Likewise.