fix curses compile warning

From hardfought; latest gcc complains that /* fall through other stuff */
doesn't match its pattern for /* fall through */ comment indicating
that omitted 'break' statement is intentional and one switch case is
deliberately continuing into the code for another.

win/curses/curswins.c

@@ -87,7 +87,7 @@ curses_create_window(int width, int height, orient orientation)
     switch (orientation) {
     default:
         impossible("curses_create_window: Bad orientation");
-        /* fall through to centre */
+        /*FALLTHRU*/
     case CENTER:
         startx = (term_cols / 2) - (width / 2);
         starty = (term_rows / 2) - (height / 2);