This patch adds support for virtual LAN (VLAN) tagging. VLAN tagging
allows multiple VLANs in a bridged network to share the same physical
network link but maintain isolation:

http://en.wikipedia.org/wiki/IEEE_802.1Q

* grub-core/net/ethernet.c: Add check, get, and set vlan tag id.
* grub-core/net/drivers/ieee1275/ofnet.c: Get vlan tag id from bootargs.
* grub-core/net/arp.c: Add check.
* grub-core/net/ip.c: Likewise.
* include/grub/net/arp.h: Add vlantag attribute.
* include/grub/net/ip.h: Likewise.

	descriptor_size==0 to avoid potential divisions by zero.

	no division by 0 occurs.

	validity.

	* grub-core/fs/nilfs2.c (grub_nilfs2_valid_sb): Check that
	block size is <= 1GiB.

The unaligned local in __aeabi_uidivmod leads to a store to a 64bit
value at an address that is not divisible by 8 (in grub_divmod64).
The compiler most likely generates a STRD instruction to store it and
this causes an exception.

Fixes Savannah bug #43632.

This includes improvements done by Leif Lindholm.

util/grub-mkconfig_lib.in(version_test_gt): "echo -n" is not really needed,
final newline is stripped by command substitution.

util/grub.d/10_kfreebsd.in, util/grub.d/10_linux.in,
util/grub.d/20_linux_xen.in: change how list is built, to avoid echo -n
completely.

util/grub.d/30_os-prober.in: add spaces to printed line directly

Closes 43668.