patch to add DWARF2 support for COFF

[Nick Clifton]

Hi Mark,

: > Note - you missed elf32-arm.h and elf32-mips.c which both have calls
: > to _bfd_dwarf2_find_nearestline - I have fixed these.
: 
: Sorry about that. But now there's another problem. 
: _bfd_dwarf2_find_nearest_line will probably crash with NULL as the last 
: parameter like elf32-arm.h and elf32-mips.c pass.

Ah, OK - I have changed the files to pass:

  &elf_tdata (abfd)->dwarf2_find_line_info

instead.

Cheers
	Nick