add ipv6only to configure echo and add configure parameter to xrdp -h output

.gitignore

@@ -43,3 +43,4 @@ sesman/sesman.ini
 stamp-h1
 xrdp/xrdp
 xrdp/xrdp.ini
+configure_params.h

configure.ac

@@ -58,7 +58,7 @@ AC_ARG_WITH([socketdir],
 AC_SUBST([socketdir], [$with_socketdir])
 
 AC_ARG_WITH([systemdsystemunitdir],
-        AS_HELP_STRING([--with-systemdsystemunitdir=DIR], [Directory for systemd service files]),
+        AS_HELP_STRING([--with-systemdsystemunitdir=DIR], [Directory for systemd service files, no to disable]),
         [], [
 if test "x$linux" = xyes; then
   with_systemdsystemunitdir=$($PKG_CONFIG --variable=systemdsystemunitdir systemd)
@@ -385,6 +385,7 @@ echo "  painter         $enable_painter"
 echo "  pixman          $enable_pixman"
 echo "  fuse            $enable_fuse"
 echo "  ipv6            $enable_ipv6"
+echo "  ipv6only        $enable_ipv6only"
 echo "  vsock           $enable_vsock"
 echo "  pam             $enable_pam"
 echo "  kerberos        $enable_kerberos"
@@ -396,3 +397,4 @@ echo "  exec_prefix             $exec_prefix"
 echo "  libdir                  $libdir"
 echo "  bindir                  $bindir"
 echo "  sysconfdir              $sysconfdir"
+echo "#define CONFIGURE_STRING \"$@\"" > configure_params.h

xrdp/xrdp.c

@@ -24,6 +24,7 @@
 
 #include "xrdp.h"
 #include "log.h"
+#include "configure_params.h"
 
 #if !defined(PACKAGE_VERSION)
 #define PACKAGE_VERSION "???"
@@ -62,6 +63,10 @@ print_version(void)
 void
 print_help(void)
 {
+#if defined(CONFIGURE_STRING)
+    g_writeln("xrdp configure command line parameters [%s]", CONFIGURE_STRING);
+    g_writeln("%s", "");
+#endif
     g_writeln("Usage: xrdp [options]");
     g_writeln("   -h, --help       show help");
     g_writeln("   -n, --nodaemon   don't fork into background");