in display_string(), if column is less than start_col and the

in display_string(), if column is less than start_col and the
character's a tab, which can be possible if there are enough tabs and
the terminal size is sufficiently large, don't try to display it using
control_mbrep()

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@3014 35c25a1d-7b9e-4130-9fde-d3aeb78583b8