[PR rtl-optimization/107182] Clear EDGE_CROSSING for jump->ret optimization

[PR rtl-optimization/107182] Clear EDGE_CROSSING for jump->ret optimization

When turning a jump to a return into a return, we need to clear EDGE_CROSSING
of the fallthru edge to prevent a checking failure.

I considered not applying the transformation when the edge has EDGE_CROSSING
set, but it still seems like we ought to eliminate the unnecessary jump in
that case.

gcc/
	PR rtl-optimization/107182
	* cfgrtl.cc (fixup_reorder_chain): When optimizing a jump to a
	return, clear EDGE_CROSSING on the appropriate edge.