(add[hs]i3): Only use two addq.w or subq.w instructions when...

(add[hs]i3): Only use two addq.w or subq.w instructions when...

(add[hs]i3): Only use two addq.w or subq.w instructions
when adding or subtracting constants 8 < N < 16 on TARGET_CPU32.
Use lea instead of add.w when adding 16 bit constants to address
registers on all but TARGET_68040.

From-SVN: r13265