UAPI: x86: Fix the test_get_len tool

Fix the x86 test_get_len tool to have the right include paths in the right
order (it includes a non-exported kernel header directly), otherwise errors
like the following occur:

/data/fs/linux-2.6-hdr/include/linux/types.h:18:26: error: conflicting types for 'fd_set'
/usr/include/sys/select.h:78:5: note: previous declaration of 'fd_set' was here

and

/data/fs/linux-2.6-hdr/include/linux/string.h:42:12: error: expected identifier or '(' before '__extension__'

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>