always keep x_cols and x_lins valid; check once at start including tty init

if we find any, but not later; do not check on every read

⇒ allows changing COLUMNS and LINES (independent of each other, or both)
  for script shells by passing them in an environment setting, even if
  we get a tty; interactive shells still check before each line is read…

reported by the PLD guys, thanks

misc.c

@@ -30,7 +30,7 @@
 #include <grp.h>
 #endif
 
-__RCSID("$MirOS: src/bin/mksh/misc.c,v 1.183 2012/03/23 20:07:11 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/misc.c,v 1.184 2012/03/23 21:58:22 tg Exp $");
 
 /* type bits for unsigned char */
 unsigned char chtypes[UCHAR_MAX + 1];
@@ -1174,10 +1174,6 @@ print_columns(struct shf *shf, int n,
 	++max_oct;
 	str = alloc(max_oct, ATEMP);
 
-	/* ensure x_cols is valid first */
-	if (x_cols < MIN_COLS)
-		change_winsz();
-
 	/*
 	 * We use (max_col + 1) to consider the space separator.
 	 * Note that no space is printed after the last column