IBM zSystems: Do not propagate scheduler state across basic blocks [PR108102]

IBM zSystems: Do not propagate scheduler state across basic blocks [PR108102]

So far we propagate scheduler state across basic blocks within EBBs and
reset the state otherwise.  In certain circumstances the entry block of
an EBB might be empty, i.e., no_real_insns_p is true.  In those cases
scheduler state is not reset and subsequently wrong state is propagated
to following blocks of the same EBB.

Since the performance benefit of tracking state across basic blocks is
questionable on modern hardware, simply reset the state for each basic
block.

Fix also resetting f{p,x}d_longrunning.

gcc/ChangeLog:

	PR target/108102
	* config/s390/s390.cc (s390_bb_fallthru_entry_likely): Remove.
	(struct s390_sched_state): Initialise to zero.
	(s390_sched_variable_issue): For better debuggability also emit
	the current side.
	(s390_sched_init): Unconditionally reset scheduler state.