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.

sysa/flex-2.5.11/patches/yyin.patch

@@ -1,43 +0,0 @@
-SPDX-FileCopyrightText: 2021 Andrius Štikonas <andrius@stikonas.eu>
-SPDX-FileCopyrightText: 2019-2020 Giovanni Mascellani <gio@debian.org>
-SPDX-FileCopyrightText: 2021 fosslinux <fosslinux@aussies.space>
-
-SPDX-License-Identifier: BSD-2-Clause
-
-yyin has an odd redefinition error in scan.l, so we ensure that we don't
-acidentally re-declare it.
-
-diff --git flexdef.h flexdef.h
-index 3eb710a..94ef024 100644
---- flexdef.h
-+++ flexdef.h
-@@ -421,7 +421,7 @@ extern int yymore_really_used, reject_really_used;
-  */
- 
- extern int datapos, dataline, linenum, out_linenum;
--extern FILE *skelfile, *yyin, *backing_up_file;
-+extern FILE *skelfile, *backing_up_file;
- extern const char *skel[];
- extern int skel_ind;
- extern char *infilename, *outfilename, *headerfilename;
-@@ -432,6 +432,10 @@ extern char **input_files;
- extern int num_input_files;
- extern char *program_name;
- 
-+#ifndef yyin_defined
-+extern FILE* yyin;
-+#endif
-+
- extern char *action_array;
- extern int action_size;
- extern int defs1_offset, prolog_offset, action_offset, action_index;
---- scan.l
-+++ scan.l
-@@ -32,6 +32,7 @@
- /*  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR */
- /*  PURPOSE. */
- 
-+#define yyin_defined
- #include "flexdef.h"
- #include "parse.h"
-