tool/boot: add chain_loader 'unzip'

'unzip' can uncompress and load raw multiboot images and ELF files.

Usage together with the PXE bootloader ease life running the muen hypervisor
together with a Genode/x86_64 VM, where the raw boot image is typically quite
large.

Ref #2358

tool/boot/README

@@ -28,3 +28,12 @@ code respectively the download source of binaries are described below.
   of the modified Grub 0.97 were obtained from
   http://os.inf.tu-dresden.de/~adam/grub.
 
+:'unzip'
+
+  The 'unzip' tool is part of the 'morbo' toolchain available under GPL.
+  The toolchain was obtained from https://github.com/TUD-OS/morbo.
+  For Genode the unzip was modified so that raw binary images with a Multiboot
+  OS header can be loaded.
+  The changes are available on the genode_bender branch of
+  https://github.com/skalk/morbo.git.
+

tool/run/load/tftp

@@ -38,6 +38,8 @@ proc install_pxe_bootloader_to_run_dir { } {
 	exec chmod a+r [run_dir]/boot/pulsar
 	exec cp [genode_dir]/tool/boot/bender [run_dir]/boot/bender
 	exec chmod a+r [run_dir]/boot/bender
+	exec cp [genode_dir]/tool/boot/unzip [run_dir]/boot/unzip
+	exec chmod a+r [run_dir]/boot/unzip
 }