AVR: target/116953 - ICE due to operands clobber in avr_out_sbxx_branch.

	PR target/116953
gcc/
	* config/avr/avr.cc (avr_out_sbxx_branch): Work on a copy of
	the operands rather than on operands itself, which is just
	recog_data.operand and may be clobbered by jump_over_one_insn_p.
gcc/testsuite/
	* gcc.target/avr/torture/pr116953.c: New test.