PR22509 - Null pointer dereference on coff_slurp_reloc_table

This extends the commit 4581a1c7 fix to more targets, which
hardens BFD a little.  I think the real underlying problem was the
bfd_canonicalize_reloc call in load_specific_debug_section which
passed a NULL for "symbols".  Fix that too.

	PR 22509
bfd/
	* aoutx.h (swap_ext_reloc_out): Gracefully handle NULL symbols.
	* i386lynx.c (swap_ext_reloc_out): Likewise.
	* pdp11.c (pdp11_aout_swap_reloc_out): Likewise.
	* coff-tic30.c (reloc_processing): Likewise.
	* coff-tic4x.c (tic4x_reloc_processing): Likewise.
	* coff-tic54x.c (tic54x_reloc_processing): Likewise.
	* coff-z80.c (reloc_processing): Likewise.
	* coff-z8k.c (reloc_processing): Likewise.
	* ecoff.c (ecoff_slurp_reloc_table): Likewise.
	* som.c (som_set_reloc_info): Likewise.
binutils/
	* objdump.c (load_specific_debug_section): Pass syms to
	bfd_canonicalize_reloc.