IRA: Don't create new regs for debug insns (PR80429)

In split_live_ranges_for_shrink_wrap IRA also splits regs that are
only used in debug insns, leading to -fcompare-debug failures.


	PR rtl-optimization/80429
	* ira.c (split_live_ranges_for_shrink_wrap): Don't split regs that
	are only used in debug insns.

From-SVN: r246991