* longlong.h (__x86_64__): Add definitions for add_ssaaaa,
        sub_ddmmss, umul_ppmm, udiv_qrnnd, count_leading_zeros and
        count_trailing_zeros.
        (__i386__): Implement count_leading_zeros using __builtin_clz().
        Implement count_trailing_zeros usign __builtin_ctz().

From-SVN: r124832