re PR rtl-optimization/83620 (ICE: in assign_by_spills, at lra-assigns.c:1470: unable to find a register to spill with -flive-range-shrinkage --param=max-sched-ready-insns=0)

	PR rtl-optimization/86620
	* params.def (max-sched-ready-insns): Bump minimum value to 1.

	* gcc.dg/pr64935-2.c: Use --param=max-sched-ready-insns=1
	instead of --param=max-sched-ready-insns=0.
	* gcc.target/i386/pr83620.c: New test.
	* gcc.dg/pr83620.c: New test.

From-SVN: r256729