[PR97847] IRA: Skip abnormal critical edge splitting

PPC64 can generate jumps with clobbered pseudo-regs and a BB with
such jump can have abnormal output edges.  IRA hits an assert when trying
to split abnormal critical edge to deal with asm goto output reloads
later.  The patch just skips splitting abnormal edges.  It is assumed
that asm-goto with output reloads can not be in BB with output abnormal edges.

gcc/ChangeLog:

	PR target/97847
	* ira.c (ira): Skip abnormal critical edge splitting.