render: ime: don’t render pre-edit string in grid while searching

While doing a scrollback search, the pre-edit string should be
rendered in the search box, not in the grid.

Note that we don’t yet support IME in scrollback search mode. This
patch simply prevents the pre-edit text being rendered in the grid,
in the “background”, while searching.

render.c

@@ -1029,6 +1029,9 @@ render_ime_preedit(struct terminal *term, struct buffer *buf)
     if (likely(term->ime.preedit.cells == NULL))
         return;
 
+    if (unlikely(term->is_searching))
+        return;
+
     /* Adjust cursor position to viewport */
     struct coord cursor;
     cursor = term->grid->cursor.point;