gitweb: incorrect search form layout when $site_header is in use

> When $site_header is in use and some vertical space is added to the top
> of the web page, the search layout with CSS
> div.search {
>         position: absolute;
>         top: 56px;
>         right: 12px
> }
> is incorrect and ends up to cover the git logo.
> 
> Correcting this by using "position: inherit;" is complicated and may
> involve some code reorganization between
>    git_header_html();   and    git_print_page_nav(...);
> 
> Please forward this upstream for correction.