[ping] Add discriminators to DWARF line table

[Cary Coutant]

Most recent patch: http://gcc.gnu.org/ml/gcc-patches/2009-04/msg02388.html

Original posting with background info:
http://gcc.gnu.org/ml/gcc-patches/2009-04/msg01679.html

-cary


	* basic-block.h (struct basic_block_def): Add discriminator field.
	* dbxout.c (dbxout_source_line): Add new parameter.  Change all
	callers.
	* debug.c (do_nothing_debug_hooks): Add additional entry.
	(debug_nothing_int_charstar_int): New function.
	* debug.h (struct gcc_debug_hooks): Add parameter to source_line
	hook.
	(debug_nothing_int_charstar_int): New declaration.
	* dwarf2out.c (dwarf2out_source_line): Add new parameter.  Write
	discriminator value in .loc directive.
	* final.c (last_discriminator): New variable.
	(discriminator): New variable.
	(final_start_function): Initialize above variables, pass current
	discriminator to debug hook.
	(notice_source_line): Check for discriminator change.
	* gimple-pretty-print.c (dump_bb_header): Print discriminator value.
	* sdbout.c (sdbout_source_line): New parameter.
	* tree-cfg.c (struct locus_discrim_map): New structure type.
	(discriminator_per_locus): New hash table.
	(build_gimple_cfg): Allocate and free discriminator hash table.
	(make_edges): Call assign_discriminator.
	(locus_map_hash): New function.
	(locus_map_eq): New function.
	(next_discriminator_for_locus): New function.
	(same_line_p): New function.
	(assign_discriminator): New function.
	(make_cond_expr_edges): Call assign_discriminator.
	(make_gimple_switch_edges): Likewise.
	(first_non_label_stmt): New function.
	* vmsdbgout.c (vmsdbgout_source_line): Add new parameter.  Change
	all callers.
	* xcoffout.c (xcoffout_source_line): Add new parameter.

	* configure.ac (gcc_cv_as_discriminator): New configury check for
	gas support for discriminator.
	* configure: Regenerate.
	* config.in: Regenerate.