Make "git help" react to window size correctly

Currently the git "show commands" function will react to the environment
variable COLUMNS, or just default to a width of 80 characters.

That's just soo eighties. Nobody sane sets COLUMNS any more, unless they
need to support some stone-age software from before the age of steam
engines, SIGWINCH and TIOCGWINSZ.

So get with the new century, and use TIOCGWINSZ to get the terminal size.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git.c

@@ -8,6 +8,7 @@
 #include <errno.h>
 #include <limits.h>
 #include <stdarg.h>
+#include <sys/ioctl.h>
 #include "git-compat-util.h"
 
 #ifndef PATH_MAX
@@ -26,6 +27,16 @@ static int term_columns(void)
 	if (col_string && (n_cols = atoi(col_string)) > 0)
 		return n_cols;
 
+#ifdef TIOCGWINSZ
+	{
+		struct winsize ws;
+		if (!ioctl(1, TIOCGWINSZ, &ws)) {
+			if (ws.ws_col)
+				return ws.ws_col;
+		}
+	}
+#endif
+
 	return 80;
 }