* config/arc/constraints.md (Cn0): New constraint.
        * config/arc/arc.md (doloop_begin): Allocate uid for loop
        end, and poke it into the pattern.
        (doloop_end_i): Change operand 2 alternative 1 to ???Cn0.
        * config/arc/arc.c (arc_reorg): Use doloop_end id provided
        by the doloop_begin expander.
        * config/arc/arc.c (arc_expand_builtin): Fix signedness of align /
        numBits.