RISC-V: Refine frm emit after bb end in succ edges

RISC-V: Refine frm emit after bb end in succ edges

This patch would like to fine the frm insn emit when we
meet abnormal edge in the loop. Conceptually, we only need
to emit once when abnormal instead of every iteration in
the loop.

This patch would like to fix this defect and only perform
insert_insn_end_basic_block when at least one succ edge is
abnormal.

gcc/ChangeLog:

	* config/riscv/riscv.cc (riscv_frm_emit_after_bb_end): Only
	perform once emit when at least one succ edge is abnormal.

Signed-off-by: Pan Li <pan2.li@intel.com>
(cherry picked from commit 177ca16b615d285f419cf2ab0337bc01f7be09db)