[gtk-doc] configure.ac: Generate xz tarball with ustar format by default

[Stefan Kost <stefkost src gnome org>]

commit ec9383be7dcf20e50c6d2e0ef45ffc48a9132977
Author: Javier JardÃn <jjardon gnome org>
Date:   Thu Jun 16 18:21:06 2011 +0100

    configure.ac: Generate xz tarball with ustar format by default

 configure.ac |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 078d522..52cdadc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -13,13 +13,13 @@ AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_SRCDIR([gtkdoc-common.pl.in])
 AC_CONFIG_AUX_DIR([build-aux])
 
-AM_INIT_AUTOMAKE([check-news std-options -Wno-portability])
+AM_INIT_AUTOMAKE([1.11 check-news std-options -Wno-portability tar-ustar no-dist-gzip dist-xz])
 AM_MAINTAINER_MODE([enable])
 
 # Support silent build rules, requires at least automake-1.11. Disable
 # by either passing --disable-silent-rules to configure or passing V=1
 # to make
-m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
+AM_SILENT_RULES([yes])
 
 dnl Forcing a non-null ACTION-IF-NOT-FOUND disables scrollkeeper if
 dnl gnome-doc-utils is not found but does not invalidate the build.