autogen.sh: add code to re-run configure afterwards

Add code to autogen.sh to (re-)run configure, with preserved
configuration.

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

Makefile.in

@@ -475,10 +475,10 @@ travis: nasm$(X)
 	$(PYTHON3) travis/nasm-t.py run
 
 #
-# Rules to run autoreconf if necessary
+# Rules to run autogen if necessary
 #
 configure: configure.ac autoconf/aclocal.m4
-	autoreconf
+	sh autogen.sh --recheck
 
 config.status: configure
 	@if [ ! -f config.status ]; then \

autogen.sh

@@ -2,6 +2,12 @@
 #
 # Run this script to regenerate autoconf files
 #
+recheck=false
+if [ x"$1" = x--recheck ]; then
+    recheck=true
+    config=$(sh config.status --config 2>/dev/null)
+fi
+
 mkdir -p autoconf autoconf/aux config
 autolib="`automake --print-libdir`"
 for prg in install-sh compile config.guess config.sub; do
@@ -18,3 +24,8 @@ rm -rf autoconf/m4.old
 autoheader -B autoconf
 autoconf -B autoconf
 rm -rf autom4te.cache config.log config.status config/config.h Makefile
+
+if $recheck; then
+    # This bizarre statement has to do with how config.status quotes its output
+    echo exec sh configure $config | sh -
+fi