Bump bootloader version, support for booting KASLR amd64 kernels.

Bump bootloader version for memory disk image changes.

branches: 1.15.4; 1.15.14; 1.15.18;
Add VESA VBE/DDC EDID support for determining the monitor's preferred
video mode. "vesa on" will now select the preferred mode @ 8bpp if it can
be determined and is supported by the display adapter, otherwise it will
use 640x480 @ 8bpp.

add support for passing image files to the kernel with the 'splash' keyword:

vesa on;splash /netbsd.jpg;boot -z

branches: 1.13.2; 1.13.4;
Pass a 64-bit boot partition base LBA into x86 /boot,
while maintaining compatibility with existing bootxx code.

NetBSD/x86 BIOS Boot 5.6: now with GUID Partition Table support.

Note stack/heap changes made in revision 1.47 of Makefile.boot with version 5.5.

branches: 1.10.4;
Bump bootloader version for VBE changes.

branches: 1.9.4;
For the x86 boot loader, autoload a kernel module corresponding to the
root file system type.

branches: 1.8.2;
Add "multiboot" command to boot multiboot compliant kernels like Xen.
Patch provided by Robert Swindell with fixes for the command line
parsing and addition of passing module options from me. The kernel now
always gets the full string for modules like for the command line,
everything before the first space/tab is the path name of the module.

Update the version numbers following commit, and make them all identical.

branches: 1.6.2; 1.6.4; 1.6.6;
- Give x86 BIOS boot the ability to load new style modules and pass them
into the kernel. Based on a patch by jmcneill@, with many fixes and
improvements by me.

- Put MEMORY_DISK_DYNAMIC and MODULAR into the GENERIC kernels, so that
you can load miniroot.kmod from the boot blocks and boot into the
installer!

branches: 1.5.74; 1.5.76; 1.5.78;
merge ktrace-lwp.

Add support for cd9660 file system to the i386 BIOS bootloader.

Add support for passing booted wedge information to the kernel.

Overhaul MBR handling (part 1):

<sys/bootblock.h>:
* Added definitions for the Master Boot Record (MBR) used by
a variety of systems (primarily i386), including the format
of the BIOS Parameter Block (BPB).
This information was cribbed from a variety of sources
including <sys/disklabel_mbr.h> which this is a superset of.

As part of this, some data structure elements and #defines
were renamed to be more "namespace friendly" and consistent
with other bootblocks and MBR documentation.
Update all uses of the old names to the new names.

<sys/disklabel_mbr.h>:
* Deprecated in favor of <sys/bootblock.h> (the latter is more
"host tool" friendly).

amd64 & i386:
* Renamed /usr/mdec/bootxx_dosfs to /usr/mdec/bootxx_msdos, to
be consistent with the naming convention of the msdosfs tools.

* Removed /usr/mdec/bootxx_ufs, as it's equivalent to bootxx_ffsv1
and it's confusing to have two functionally equivalent bootblocks,
especially given that "ufs" has multiple meanings (it could be
a synonym for "ffs", or the group of ffs/lfs/ext2fs file systems).

* Rework pbr.S (the first sector of bootxx_*):
+ Ensure that BPB (bytes 11..89) and the partition table
(bytes 446..509) do not contain code.
+ Add support for booting from FAT partitions if BOOT_FROM_FAT
is defined. (Only set for bootxx_msdos).
+ Remove "dummy" partition 3; if people want to installboot(8)
these to the start of the disk they can use fdisk(8) to
create a real MBR partition table...
+ Compile with TERSE_ERROR so it fits because of the above.
Whilst this is less user friendly, I feel it's important
to have a valid partition table and BPB in the MBR/PBR.

* Renamed /usr/mdec/biosboot to /usr/mdec/boot, to be consistent
with other platforms.

* Enable SUPPORT_DOSFS in /usr/mdec/boot (stage2), so that
we can boot off FAT partitions.

* Crank version of /usr/mdec/boot to 3.1, and fix some of the other
entries in the version file.

installboot(8) (i386):
* Read the existing MBR of the filesystem and retain the BIOS
Parameter Block (BPB) in bytes 11..89 and the MBR partition
table in bytes 446..509. (Previously installboot(8) would
trash those two sections of the MBR.)

mbrlabel(8):
* Use sys/lib/libkern/xlat_mbr_fstype.c instead of homegrown code
to map the MBR partition type to the NetBSD disklabel type.


Test built "make release" for i386, and new bootblocks verified to work
(even off FAT!).

branches: 1.1.2;
Add files for 2nd stage boot loader