Ticket #2953: (edit_move_to_prev_col): fix floating point exception.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>

src/editor/edit.c

@@ -3256,13 +3256,17 @@ edit_move_to_prev_col (WEdit * edit, off_t p)
         edit->over_col = 0;
         if (option_fake_half_tabs && is_in_indent (edit))
         {
+            long fake_half_tabs;
+
             edit_update_curs_col (edit);
-            if (space_width != 0 && edit->curs_col % (HALF_TAB_SIZE * space_width) != 0)
+
+            fake_half_tabs = HALF_TAB_SIZE * space_width;
+            if (fake_half_tabs != 0 && edit->curs_col % fake_half_tabs != 0)
             {
                 int q;
 
                 q = edit->curs_col;
-                edit->curs_col -= (edit->curs_col % (HALF_TAB_SIZE * space_width));
+                edit->curs_col -= (edit->curs_col % fake_half_tabs);
                 p = edit_bol (edit, edit->curs1);
                 edit_cursor_move (edit,
                                   edit_move_forward3 (edit, p, edit->curs_col, 0) - edit->curs1);