Fix to output_strlen_unroll - avoids compiler core dump

[Jim Kingdon]

> > 	* config/i386/i386.c (output_strlen_unroll): Don't write xops[7]
> . . .
> Thanks.  Applied to mainline.

Woohoo!

If I keep up this "within a day, both fix a nontrivial bug and get my
patch accepted" thing for too much longer, I'm in danger of getting a
dangerously swelled head :-).

Thanks to you for taking the time to look at my patch.