Limit VOLUME_LABEL (first argument to the mkisoimages scripts)
to 32 characters.

This is a direct commit to stable/10, as UEFI support natively
exists for 11.0-CURRENT and unsupported in 9-STABLE.

Submitted by: Rick Miller
PR: 210463
Sponsored by: The FreeBSD Foundation

MFC r293831:

Increase efiboot.img size used in ISO creation

This changes mkisoimages-uefi.sh instead of mkisoimages.sh in r293831 due to
refactor not MFC'ed.

Sponsored by: Multiplay

MFC r264995 (nwhitehorn):

Add script to setup bootable CD ISOs for both BIOS and EFI systems.
Tested and working on QEMU. Actually using this script as the regular
image generator, like with the memstick one, will require that the
kernel support EFI too. In particular, the following two things are
required:
1. vt(9) be the default console driver
2. vt_efifb and vt_vga be able to coexist usefully in the same kernel

One other note here is that this requires newfs_msdos and mdconfig,
which is really ugly. NetBSD's makefs at least seems to support FAT
now. If that actually works, it should be imported and we can get rid
of the mdconfig mess.

Approved by: re
Relnotes: Yes
Sponsored by: The FreeBSD Foundation

MFC r264995 (nwhitehorn):

Add script to setup bootable CD ISOs for both BIOS and EFI systems.
Tested and working on QEMU. Actually using this script as the regular
image generator, like with the memstick one, will require that the
kernel support EFI too. In particular, the following two things are
required:
1. vt(9) be the default console driver
2. vt_efifb and vt_vga be able to coexist usefully in the same kernel

One other note here is that this requires newfs_msdos and mdconfig,
which is really ugly. NetBSD's makefs at least seems to support FAT
now. If that actually works, it should be imported and we can get rid
of the mdconfig mess.

Approved by: re
Relnotes: Yes
Sponsored by: The FreeBSD Foundation