(find_split_point, case SET): If SET_SRC is NE and STORE_FLAG_VALUE is -1, see if we can convert into NEG of shift.

(find_split_point, case SET): If SET_SRC is NE and
STORE_FLAG_VALUE is -1, see if we can convert into NEG of shift.
(force_to_mode, case NE): Make condition stricter.

From-SVN: r13370