Convert lib/Makefile.am into lib/local.mk.

The real problem is rather gnulib.mk, which itself is extracted from a
Makefile.am that gnulib expects to the "recursive".  The tool
prefix-gnulib-mk converts such a gnulib.mk to be non-recursive.  Also,
some AC_SUBST variables need to be adjusted.

	* etc/prefix-gnulib-mk: New.
	* bootstrap (slurp): Use it to convert further gnulib.mk.
	* lib/Makefile.am: Rename as...
	* lib/local.mk: this.
	Adjust to be prefixed.
	* Makefile.am, configure.ac: Adjust.
	* src/local.mk (AM_CPPFLAGS): Extend it, don't define it.

etc/prefix-gnulib-mk

@@ -0,0 +1,149 @@
+#! /usr/bin/perl -w
+
+use strict;
+use IO::File;
+
+my $prefix = "lib/";
+
+# contents ($FILE_NAME)
+# ---------------------
+sub contents ($)
+{
+  my ($file) = @_;
+  local $/;			# Turn on slurp-mode.
+  my $f = new IO::File "< $file" or die "$file";
+  my $contents = $f->getline or die "$file";
+  $f->close;
+  return $contents;
+}
+
+# prefix_word ($WORD)
+# -------------------
+# Do not prefix special words such as variable dereferences.  Also,
+# "Makefile" is really "Makefile", since precisely there is no
+# lib/Makefile.
+sub prefix_word ($)
+{
+  local ($_) = @_;
+  $_ = $prefix . $_
+    unless m{^\$\(\w+\)} || $_ eq "Makefile";
+  return $_;
+}
+
+
+# prefix_words ($TEXT)
+# --------------------
+sub prefix_words ($)
+{
+  local ($_) = @_;
+  s{(\S+)}{prefix_word($1)}gem;
+  return $_;
+}
+
+
+# prefix_assignment ($LHS-AND-ASSIGN-OP, $RHS)
+# --------------------------------------------
+sub prefix_assignment ($$)
+{
+  my ($lhs_and_assign_op, $rhs) = @_;
+  my $res;
+
+  # Some variables are initialized by gnulib.mk, and we don't want
+  # that.  Change '=' to '+='.
+  if ($lhs_and_assign_op =~ /^(SUBDIRS|EXTRA_DIST|BUILT_SOURCES|SUFFIXES|MOSTLYCLEANFILES|CLEANFILES|DISTCLEANFILES|MAINTAINERCLEANFILES|AM_CPPFLAGS|AM_GNU_GETTEXT) =/)
+    {
+      $lhs_and_assign_op =~ s/=/+=/;
+    }
+  # We don't want to inherit gnulib's AUTOMAKE_OPTIONS, comment them.
+  elsif ($lhs_and_assign_op =~ /^AUTOMAKE_OPTIONS =/)
+    {
+      $lhs_and_assign_op =~ s/^/# /;
+    }
+  # Don't touch suffixes.
+  elsif ($lhs_and_assign_op =~ /^SUFFIXES /)
+    {
+    }
+  # The words are (probably) paths to files in lib/: prefix them.
+  else
+    {
+      $rhs = prefix_words($rhs)
+    }
+
+  # Variables which name depend on the location: libbison_a_SOURCES =>
+  # lib_libbison_a_SOURCES.
+  $lhs_and_assign_op =~ s/(libbison)/lib_$1/g;
+
+  # Do not use gl_LIBOBJS, but its prefixed version.
+  $rhs =~ s/gl_LIBOBJS/gl_PREFIXED_LIBOBJS/g;
+
+  return $lhs_and_assign_op . $rhs;
+}
+
+# prefix $CONTENTS
+# ----------------
+# $CONTENTS is a Makefile content.  Post-process it so that each file-name
+# is prefixed with $prefix (e.g., "lib/").
+#
+# Relies heavily on the regularity of the file generated by gnulib-tool.
+sub prefix ($)
+{
+  # Work on $_.
+  local ($_) = @_;
+
+  # Prefix all the occurrence of files in rules.  If there is nothing
+  # after in the :, it's probably a phony target, or a suffix rule.
+  # Don't touch it.
+  s{^([\w.]+ *: *\w.*)$}
+   {prefix_words($1)}gem;
+
+  # Prefix files in variables.
+  s{^([\w.]+\s*\+?=)(.*)$}
+   {prefix_assignment($1, $2)}gem;
+
+  # These three guys escape all the other regular rules.
+  s{(charset\.alias|ref-add\.sed|ref-del\.sed)}{$prefix$1}g;
+  # Unfortunately, as a result we sometimes have lib/lib.
+  s{lib/lib/}{lib/}g;
+
+  # $(srcdir) is actually $(top_srcdir)/lib.
+  s{\$\(srcdir\)}{\$(top_srcdir)/lib}g;
+
+  # Sometimes, t-$@ is used instead of $@-t, which, of course, does
+  # not work when we have a $@ with a directory in it.
+  s{t-\$\@}{\$\@-t}g;
+
+  return $_;
+}
+
+# process ($IN)
+# -------------
+sub process ($)
+{
+  my ($file) = @_;
+  my ($bak) = "$file.bak";
+  rename ($file, $bak) or die;
+  my $contents = contents ($bak);
+  $contents = prefix ($contents);
+  my $out = new IO::File(">$file") or die;
+  print $out $contents;
+}
+
+process ("lib/gnulib.mk")
+
+
+### Setup "GNU" style for perl-mode and cperl-mode.
+## Local Variables:
+## perl-indent-level: 2
+## perl-continued-statement-offset: 2
+## perl-continued-brace-offset: 0
+## perl-brace-offset: 0
+## perl-brace-imaginary-offset: 0
+## perl-label-offset: -2
+## cperl-indent-level: 2
+## cperl-brace-offset: 0
+## cperl-continued-brace-offset: 0
+## cperl-label-offset: -2
+## cperl-extra-newline-before-brace: t
+## cperl-merge-trailing-else: nil
+## cperl-continued-statement-offset: 2
+## End: