rename configure.in to configure.ac for non-oldness

autogen.sh

@@ -6,7 +6,7 @@ test -z "$srcdir" && srcdir=.
 
 DIE=0
 
-(test -f $srcdir/configure.in) || {
+(test -f $srcdir/configure.ac) || {
     echo -n "**Error**: Directory $srcdir does not look like the"
     echo " top-level package directory"
     exit 1
@@ -20,7 +20,7 @@ DIE=0
   DIE=1
 }
 
-(grep "^AM_PROG_LIBTOOL" $srcdir/configure.in >/dev/null) && {
+(grep "^AM_PROG_LIBTOOL" $srcdir/configure.ac >/dev/null) && {
   (libtool --version) < /dev/null > /dev/null 2>&1 || {
     echo
     echo "**Error**: You must have libtool installed."