jam: Add binary bootloader for Raspberry Pi

* Version 17-02-2012
* Used to initialize the Raspberry Pi GPU and boot it
* License is permissive, I've also included the
  confirmation email on this license.
* Little bootloader documentation.
* Still nothing to get excited about, preliminary.

build/jam/board/raspberry_pi/cmdline.txt

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+dwc_otg.lpm_enable=0 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 rootwait
+ 

build/jam/board/raspberry_pi/info.txt

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+Some early bootloader information from Raspberry Pi foundation...
+
+Setting up the boot partition
+
+partition 1 -- FAT32, bootable flag, type 'c'
+partition 2 -- os, whatever
+
+The boot partition must contain the following files,
+get them from one of the official images:
+
+* bootcode.bin : 2nd stage bootloader, starts with SDRAM disabled
+* loader.bin : 3rd stage bootloader, starts with SDRAM enabled
+* start.elf: The GPU binary firmware image, provided by the foundation.
+* kernel.img: The OS kernel to load on the ARM processor.
+  Normally this is Linux - see instructions for compiling a kernel.
+* cmdline.txt: Parameters passed to the kernel on boot.
+
+Optional files:
+* config.txt: A configuration file read by the GPU.
+  Use this to override set the video mode, alter system clock speeds,
+  voltages, etc.
+* vlls directory: Additional GPU code, e.g. extra codecs.
+  Not present in the initial release.
+
+Additional GPU firmware images, rename over start.elf to use them:
+* arm128_start.elf : 128M ARM, 128M GPU split
+  - use this for heavy 3D work, possibly also required for some video decoding)
+* arm192_start.elf : 192M ARM, 64M GPU split
+  - this is the default
+* arm224_start.elf : 224M ARM, 32M GPU split
+  - (use this for Linux only with no 3D or video processing.
+    Its enough for the 1080p framebuffer, but not much else)

build/jam/board/raspberry_pi/license.txt

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+-------- Original Message --------
+Subject: Re: What is the arm224_start.elf license info?
+Date: 05.03.2012 14:18
+From: Eben Upton
+To: Alexander von Gluck
+
+Hi Alex
+The stuff in the boot partition is released under an extremely
+permissive license - it's freely redistributable for any purpose
+related to Raspberry Pi (such as yours).
+
+Cheers
+Eben Upton
+Executive Director, Raspberry Pi Foundation
+
+On Sun, Mar 4, 2012 at 2:13 PM, Alexander von Gluck
+<kallisti5@unixzen.com> wrote:
+> What is the license for the arm224_start.elf and friends GPU first stage
+> stuff?
+>
+> I am toying with a Haiku port and thought it would be nice to add these to
+> our repository.
+>
+> Thanks!
+>  -- Alex