Avoid unexpected hlsearch

[KSR-Yasuda]

After search and :nohl to turn off the highlight,
winresizer's window focus mode unexpectedly enable the search highlight.

/ /         " Search something
:nohl       " Turn off the highlight

<c-q>f      " Run winresizer focus mode
l           " Move to other window
r           " and back
            " Then, the highlight is turned on somehow.

To avoid this, disable '&hlsearch' option in winresizer operations.