(expand_assignment): If WANT_VALUE is 0, return NULL.

(store_expr): Likewise.
Rename arg SUGGEST_REG to WANT_VALUE.
Never return TARGET if WANT_VALUE unless BLKmode.
Instead, return TEMP or a value copied from TARGET.
Pass 0 for WANT_VALUE in recursive calls that ignore value.

(expand_expr, case PLUS_EXPR): Goto binop2 not
both_summands if we should not be returning a plus.

(do_tablejump) [PIC_CASE_VECTOR_ADDRESS]: If pic,
copy INDEX to a register early, to avoid invalid address later.

From-SVN: r5108