MFC: r263121

Re-format the license to conform to our BSD license template as much
as possible.  This does not change the wording in any way.

Remove the 3rd clause ("advertising clause") of the BSD license as
permitted by the University of Berkeley on July 22, 1999.  While the
clause itself mentions Lawrence Berkeley Laboratory, UCB is the sole
copyright holder of this file.

Reviewed by:    imp, emaste, eadler
MFC: r262484

In puthdr(), start the ELF .data section on a new page, as this is
what btxldr expects (.set MEM_DATA,start+0x1000 in btxldr.S).

This makes resulting ELF binaries bootable with grub, gptboot and boot2.

PR:             153801
Submitted by:   Gleb Kurtsou <gleb.kurtsou at gmail.com>
Tested by:      Ruben Kerkhof <ruben at rubenkerkhof.com>
Glanced at by:  jhb, peter