Add COLUMNS support to cols(1)

First attempt to see if COLUMNS is set, if that fails an ioctl()
is issued to find the width of the output device.  If that fails
as well, we default to 65 chars per line.

cols.c

@@ -31,6 +31,7 @@ main(int argc, char *argv[])
 	size_t i, l, col, len, bytes, maxlen = 0;
 	struct winsize w;
 	FILE *fp;
+	char *p;
 
 	ARGBEGIN {
 	case 'c':
@@ -42,8 +43,9 @@ main(int argc, char *argv[])
 	} ARGEND;
 
 	if (cflag == 0) {
-		ioctl(STDOUT_FILENO, TIOCGWINSZ, &w);
-		if (w.ws_col != 0)
+		if ((p = getenv("COLUMNS")))
+			chars = estrtonum(p, 1, MIN(LLONG_MAX, SIZE_MAX));
+		else if (!ioctl(STDOUT_FILENO, TIOCGWINSZ, &w) && w.ws_col > 0)
 			chars = w.ws_col;
 	}