autoconf: modernize and modularize

Use my modular m4 library used for other things as well; update
autoconf macros to 2.71 standard.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

autogen.sh

@@ -1,2 +1,83 @@
-#!/bin/sh
-make autoconf
+#!/bin/sh -x
+#
+# Run this script to regenerate autoconf files
+#
+recheck=false
+for arg; do
+    case x"$arg" in
+	x--recheck)
+	    recheck=true
+	    config=$(sh config.status --config 2>/dev/null)
+	    ;;
+	x--clearenv)
+	    unset AUTOCONF AUTOMAKE ACLOCAL AUTOHEADER ACLOCAL_PATH
+	    ;;
+	*)
+	    echo "$0: unknown option: $arg" 1>&2
+	    ;;
+    esac
+done
+
+# This allows for overriding the default autoconf programs
+AUTOCONF="${AUTOCONF:-${AUTOTOOLS_PREFIX}autoconf}"
+AUTOMAKE="${AUTOMAKE:-${AUTOTOOLS_PREFIX}automake}"
+ACLOCAL="${ACLOCAL:-${AUTOTOOLS_PREFIX}aclocal}"
+AUTOHEADER="${AUTOHEADER:-${AUTOTOOLS_PREFIX}autoheader}"
+
+mkdir -p autoconf autoconf/helpers config
+autolib="`"$AUTOMAKE" --print-libdir`"
+if test ! x"$autolib" = x; then
+    for prg in install-sh compile config.guess config.sub; do
+	# Update autoconf helpers if and only if newer ones are available
+	if test -f "$autolib"/"$prg" && \
+		( set -e ; \
+		  test -f autoconf/helpers/"$prg" && sed -n \
+		    -e 's/^scriptver=/scriptversion=/' \
+		    -e 's/^timestamp=/scriptversion=/' \
+		    -e 's/^scriptversion=['\''"]?\([^'\''"]*\).*$/\1/p' \
+			  "$autolib"/"$prg" autoconf/helpers/"$prg" | \
+			  sort -c 2>/dev/null ; \
+		  test $? -ne 0 )
+	then
+	    cp -f "$autolib"/"$prg" autoconf/helpers
+	fi
+    done
+fi
+mv -f autoconf/aclocal.m4 autoconf/aclocal.m4.old
+mkdir -p autoconf/m4.old autoconf/m4
+mv -f autoconf/m4/*.m4 autoconf/m4.old/ 2>/dev/null || true
+ACLOCAL_PATH="${ACLOCAL_PATH}${ACLOCAL_PATH:+:}`pwd`/autoconf/m4.old"
+export ACLOCAL_PATH
+"$ACLOCAL" --install --output=autoconf/aclocal.m4 -I autoconf/m4
+if test ! -f autoconf/aclocal.m4; then
+    # aclocal failed, revert to previous files
+    mv -f autoconf/m4.old/*.m4 autoconf/m4/
+    mv -f autoconf/aclocal.m4.old autoconf/aclocal.m4
+    exit 1
+fi
+rm -rf autoconf/*m4.old
+"$AUTOHEADER" -B autoconf
+"$AUTOCONF" -B autoconf
+(
+    echo '#!/bin/sh'
+    "$AUTOCONF" -B autoconf \
+		-t AC_CONFIG_HEADERS:'rm -f $*' \
+		-t AC_CONFIG_FILES:'rm -f $*'
+    echo 'rm -f config.log config.status'
+    echo 'rm -rf autom4te.cache'
+) > autoconf/clean.sh
+chmod +x autoconf/clean.sh
+sh autoconf/clean.sh
+
+rm -f configure~ || true
+
+# Try to regenerate unconfig.h if Perl is available and unconfig.pl
+# is present in the autoconf directory.
+if [ -n "$(which perl)" -a -f autoconf/unconfig.pl ]; then
+    perl autoconf/unconfig.pl . config/config.h.in config/unconfig.h
+fi
+
+if $recheck; then
+    # This bizarre statement has to do with how config.status quotes its output
+    echo exec sh configure $config | sh -
+fi