Support booting with a packaged boot loader

* Add new package haiku_loader.hpkg and move haiku_loader there. The
  package is built without compression, so that the stage 1 boot loader
  has a chance of loading it.
* Adjust the stage 1 boot loader to load the haiku_loader package and
  relocate the boot loader code accordingly.

src/data/package_infos/haiku_loader

@@ -0,0 +1,18 @@
+name			haiku_loader
+version			R1~alpha4_pm-1
+architecture	x86_gcc2
+summary			"The Haiku boot loader"
+description		"The Haiku boot loader."
+
+packager		"The Haiku build system"
+vendor			"Haiku Project"
+
+copyrights		"2001-2013 Haiku, Inc. et al"
+licenses		"MIT"
+
+provides {
+	haiku_loader=R1~alpha4_pm-1
+}
+
+requires {
+}