Make ia64 port use tags instead of labels for debug info labels.

Make ia64 port use tags instead of labels for debug info labels.
	* defaults.h (ASM_OUTPUT_DEBUG_LABEL): New.
	* tm.texi (ASM_OUTPUT_DEBUG_LABEL): Document.
	* dwarf2out.c (dwarf2out_begin_block): Use ASM_OUTPUT_DEBUG_LABEL
	instead of ASM_OUTPUT_INTERNAL_LABEL.
	(dwarf2out_end_block, dwarf2out_label): Likewise.
	* final.c (final_scan_insn, case NOTE_INSN_DELETED_LABEL): Likewise
	* config/ia64/ia64.h (ASM_OUTPUT_DEBUG_LABEL): Define.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@37174 138bc75d-0d04-0410-961f-82ee72b054a4