Fix "git help -a" terminal autosizing

When I split out the builtin commands into their own files, I left the 
include of <sys/ioctl.h> in git.c rather than moving it to the file that 
needed it (builtin-help.c).

Nobody seems to have noticed, because everything still worked, but because 
the TIOCGWINSZ macro was now no longer defined when compiling the 
"term_columns()" function, it would no longer automatically notice the 
terminal size unless your system used the ancient "COLUMNS" environment 
variable approach.

Trivially fixed by just moving the header include to the file that 
actually needs it.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/builtin-help.c b/builtin-help.c
index 10a59cc..7470faa 100644
--- a/builtin-help.c
+++ b/builtin-help.c

@@ -3,6 +3,7 @@
  *
  * Builtin help-related commands (help, usage, version)
  */
+#include <sys/ioctl.h>
 #include "cache.h"
 #include "builtin.h"
 #include "exec_cmd.h"

diff --git a/git.c b/git.c
index aa2b814..01b7e28 100644
--- a/git.c
+++ b/git.c

@@ -8,7 +8,6 @@ #include <string.h>
 #include <errno.h>
 #include <limits.h>
 #include <stdarg.h>
-#include <sys/ioctl.h>
 #include "git-compat-util.h"
 #include "exec_cmd.h"