Tidy up debugging in the ARC port of the BFD library.

Tidy up debugging in the ARC port of the BFD library.

bfd	* elf32-arc.c (PR_DEBUG): Delete.
	Fix printing of debug information.  Fix formatting of debug
	statements.
	(debug_arc_reloc): Handle symbols that are not from an input file.
	(arc_do_relocation): Remove excessive exclamation points.
	(elf_arc_relocate_section): Print an informative message if the
	relocation fails, even if debugging is not enabled.
	* arc-got.h: Fix formatting.  Fix printing of debug information.
	(new_got_entry_to_list): Use xmalloc.
	* config.bfd: use the big-endian arc vector as the default vector
	for big-endian arc targets.

ld	* testsuite/ld-arc/arc.exp: Always run the sda-relocs test in
	little endian mode.