This disables the g_return_ macros, and quite often
we rely on that. So for the sake of stability, disable
those.

Use AUTOCONF_VERSION for automake-$ver, ACLOCAL_VERSION for
aclocal-$ver, AUTOMAKE_VERSION for automake-$ver and
AUTOHEADER_VERSION for autoheader-$ver.

This removes the custom checks for the //newest// binary
version, which gets constantly outdated.

Support LT_PREREQ as the new alternative of AC_PROG_LIBTOOL. If
the latter is used, show a message with information how to switch
to LT_PREREQ.

Mike Massonnet authored Aug 27, 2011 and Nick Schermer committed Sep 08, 2011

The translations have been removed from the code -- Nick.

Use the macro shipped with pkg-config for detection of
$PKG_CONFIG. This to fix cross-build compatibility.

signal.h has an inline that redeclares __errno.

This breaks the sun studio compiler and since -g defaults
to level 2, it provides enough backtrace information.

The FreeBSD bot has some problems with this flag. Disable
it on non-linux systems, since it's not that important.

/bin/sh does not support the -n option for echo. Use printf instead,
which is independent of the shell.

This adds an extra check when XDT_AUTOGEN_CHECK_DOCS
is defined. This variable points to the directory that
should contain the xfce4-docs submodule.

If no submodule clone if found and autogen.sh is running
from within a git clone, it will automatically initialize
the submodule for the user, if not it will show an error
and abort xdt-autogen, since configure will abort too if
we continue because of missing makefile.am files.

This reverts commit 77d9703d.