Fix 4134: After deleting all entries of last page, we should display the new last page

Hi,

I tried to fix this bug: http://sourceforge.net/p/phpmyadmin/bugs/4134/

I added a control after a multi delete. We check if position is higher than number of rows. If this is true, the position is updated to display the lines of the last page.

I'm open to any comment.

Thanks,
H.