bug#7787: 23.2; wrong meaning for mouse-2 while in search mode

[Juri Linkov]

>> I don't understand how this fixes the problem above.
>
> The test case is to double-click a word, `C-s' and then `mouse-2' to
> insert it.  With the patch, that's what happens.

But only when mouse-yank-at-point is non-nil?  I still don't understand
why allowing to yank by clicking anywhere in the buffer
should depend on mouse-yank-at-point?  It allows yanking at point,
but in isearch it yanks to the search string in the echo area.