Remove the notion of "sys*"

- This idea originates from very early in the project and was, at the
  time, a very easy way to categorise things.
- Now, it doesn't really make much sense - it is fairly arbitary, often
  occuring when there is a change in kernel, but not from builder-hex0
  to fiwix, and sysb is in reality completely unnecessary.
- In short, the sys* stuff is a bit of a mess that makes the project
  more difficult to understand.
- This puts everything down into one folder and has a manifest file that
  is used to generate the build scripts on the fly rather than using
  coded scripts.
- This is created in the "seed" stage.

stage0-posix -- (calls) --> seed -- (generates) --> main steps

Alongside this change there are a variety of other smaller fixups to the
general structure of the live-bootstrap rootfs.

- Creating a rootfs has become much simpler and is defined as code in
  go.sh. The new structure, for an about-to-be booted system, is

/
-- /steps (direct copy of steps/)
-- /distfiles (direct copy of distfiles/)
-- all files from seed/*
-- all files from seed/stage0-posix/*

- There is no longer such a thing as /usr/include/musl, this didn't
  really make any sense, as musl is the final libc used. Rather, to
  separate musl and mes, we have /usr/include/mes, which is much easier
  to work with.
- This also makes mes easier to blow away later.
- A few things that weren't properly in packages have been changed;
  checksum-transcriber, simple-patch, kexec-fiwix have all been given
  fully qualified package names.
- Highly breaking change, scripts now exist in their package directory
  but NOT WITH THE packagename.sh. Rather, they use pass1.sh, pass2.sh,
  etc. This avoids manual definition of passes.
  - Ditto with patches; default directory is patches, but then any patch
    series specific to a pass are named patches-passX.

sysc/gcc-4.7.4/patches/0004-libstdc-gthr-workaround-for-musl.patch

@@ -1,41 +0,0 @@
-SPDX-FileCopyrightText: 2022 Dor Askayo <dor.askayo@gmail.com>
-SPDX-FileCopyrightText: 2015 Szabolcs Nagy <szabolcs.nagy@arm.com>
-
-SPDX-License-Identifier: GPL-2.0-or-later
-
-Backported from upstream commit 85da5c3024f731e719c4093314da8edcd1056527
-
-libstdc++ gthr workaround for musl
-
-[libstdc++-v3/]
-2015-04-22  Szabolcs Nagy  <szabolcs.nagy@arm.com>
-
-	* config/os/generic/os_defines.h (_GLIBCXX_GTHREAD_USE_WEAK): Define.
-	* configure.host (os_include_dir): Set to "os/generic" for linux-musl*.
-
-From-SVN: r222329
-
---- libstdc++-v3/config/os/generic/os_defines.h
-+++ libstdc++-v3/config/os/generic/os_defines.h
-@@ -33,4 +33,9 @@
- // System-specific #define, typedefs, corrections, etc, go here.  This
- // file will come before all others.
- 
-+// Disable the weak reference logic in gthr.h for os/generic because it
-+// is broken on every platform unless there is implementation specific
-+// workaround in gthr-posix.h and at link-time for static linking.
-+#define _GLIBCXX_GTHREAD_USE_WEAK 0
-+
- #endif
---- libstdc++-v3/configure.host
-+++ libstdc++-v3/configure.host
-@@ -242,6 +242,9 @@ case "${host_os}" in
-   freebsd*)
-     os_include_dir="os/bsd/freebsd"
-     ;;
-+  linux-musl*)
-+    os_include_dir="os/generic"
-+    ;;
-   gnu* | linux* | kfreebsd*-gnu | knetbsd*-gnu)
-     if [ "$uclibc" = "yes" ]; then
-       os_include_dir="os/uclibc"