[patch] : Optimize search_n

[Paolo Carlini]

chris jefferson wrote:

>This backports the recent optimization to search_n back to so_6. The
>only major difference is that it doesn't use find_if in the predicated
>case. It never did, and to enable this would involve copying a bunch of
>framework.
>
>Tested on powerpc-darwin
>
Ok, everything seems fine, modulo a couple of trivial reformattings;
regtested ok on x86-linux too. I'm going to apply the patch to mainline,
as far as I'm concerned the last change to the algorithms for 4.1,
modulo pure bug fixes.

Paolo.