* sched-int.h (struct deps): New field libcall_block_tail_insn.
        * sched_deps.c (init_deps): Initialize libcall_block_tail_insn.
        * sched_deps.c (sched_analyze_insn): If libcall_block_tail_insn
        is set, then mark the current insn as being part of a libcall
        scheduling group.
        (sched_analyze): Set and clear libcall_block_tail_insn appropriately.

        * haifa-sched.c (schedule_block): Do not count USE or CLOBBER
        insns against the issue rate.

From-SVN: r54251