GNU Autoconf manual states (section 3.1):
Previous versions of Autoconf promoted the name configure.in, which
is somewhat ambiguous (the tool needed to process this file is not
described by its extension), and introduces a slight confusion with
config.h.in and so on (for which '.in' means "to be processed by
configure"). Using configure.ac is now preferred.
PKG_NAME="evolution-data-server"
REQUIRED_AUTOMAKE_VERSION=1.6
-(test -f $srcdir/configure.in \
+(test -f $srcdir/configure.ac \
&& test -f $srcdir/ChangeLog \
&& test -d $srcdir/calendar) || {
echo -n "**Error**: Directory "\`$srcdir\'" does not look like the"