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.

steps/coreutils-5.0/patches/tac-uint64.patch

@@ -0,0 +1,27 @@
+SPDX-FileCopyrightText: 2022 Andrius Štikonas <andrius@stikonas.eu>
+
+SPDX-License-Identifier: GPL-2.0-or-later
+
+uint64_t is not supported in tcc 0.9.27
+--- lib/tempname.c     2002-12-01 10:40:32.000000000 +0000
++++ lib/tempname.c     2022-06-22 20:57:37.449423973 +0100
+@@ -231,8 +231,8 @@
+ {
+   int len;
+   char *XXXXXX;
+-  static uint64_t value;
+-  uint64_t random_time_bits;
++  static unsigned long long value;
++  unsigned long long random_time_bits;
+   unsigned int count;
+   int fd = -1;
+   int save_errno = errno;
+@@ -278,7 +278,7 @@
+ 
+   for (count = 0; count < attempts; value += 7777, ++count)
+     {
+-      uint64_t v = value;
++      unsigned long long v = value;
+ 
+       /* Fill in the random bits.  */
+       XXXXXX[0] = letters[v % 62];