[LVU] deal with md final_scan_insn

[LVU] deal with md final_scan_insn

Ports call final_scan_insn with seen == NULL, and then
maybe_output_next_view crashes because it assumes it's
non-NULL.  Oops.  Fixed.

for  gcc/ChangeLog

	* final.c (final_scan_insn_1): Renamed from...
	(final_scan_insn): ... this.  New wrapper, to recover
	seen from the outermost call in recursive ones.
	* config/sparc/sparc.c (output_return): Drop seen from call.
	(output_sibcall): Likewise.
	* config/visium/visium.c (output_branch): Likewise.

From-SVN: r257562