Rework bootstrap to be reproducible

* configure.ac:
* Makefile.am (SUBDIRS): Replace bootstrap/ with stage0, stage1, and
stage2.
* am/bootstrap.am: Include all files and all rules.
* meta/build-env.in (GUILE_AUTO_COMPILE): Always turn off
auto-compilation.  Take a GUILE_BOOTSTRAP_STAGE argument, which can be
stage0, stage1, stage2, or unset.  Adapt the load-compiled path
accordingly.
* meta/uninstalled-env.in: Include .go files from stage2.
* module/Makefile.am: Rework to use boostrap.am.
* module/system/base/optimize.scm (available-optimizations): Punt the
inlinable-exports machinery to -O2.
* stage0/Makefile.am:
* stage1/Makefile.am:
* stage2/Makefile.am: New files.

stage2/Makefile.am

@@ -0,0 +1,31 @@
+## Process this file with automake to produce Makefile.in.
+##
+##  	Copyright (C) 2009, 2010, 2011, 2012, 2013,
+##        2014, 2015, 2018, 2020, 2022 Free Software Foundation, Inc.
+##
+##   This file is part of GUILE.
+##
+##   GUILE is free software; you can redistribute it and/or modify it
+##   under the terms of the GNU Lesser General Public License as
+##   published by the Free Software Foundation; either version 3, or
+##   (at your option) any later version.
+##
+##   GUILE is distributed in the hope that it will be useful, but
+##   WITHOUT ANY WARRANTY; without even the implied warranty of
+##   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+##   GNU Lesser General Public License for more details.
+##
+##   You should have received a copy of the GNU Lesser General Public
+##   License along with GUILE; see the file COPYING.LESSER.  If not,
+##   write to the Free Software Foundation, Inc., 51 Franklin Street,
+##   Fifth Floor, Boston, MA 02110-1301 USA
+
+
+GUILE_WARNINGS = -W1
+GUILE_OPTIMIZATIONS = -O2
+GUILE_BOOTSTRAP_STAGE = stage2
+
+include $(top_srcdir)/am/bootstrap.am
+
+ccachedir = $(pkglibdir)/$(GUILE_EFFECTIVE_VERSION)/ccache
+nobase_ccache_DATA = $(GOBJECTS)