#137 $(docdir) conflicts with CVS Autoconf

[Stepan Kasal]

CVS Autoconf introduces docdir, which defaults to
$prefix/share/doc/packagename

xmldocs.make also defines docdir, which conflicts with
this variable. (I looked at current CVS.)

Automake issues a warning. According to my tests with
Automake 1.9.6, both definitions are outputted, and the
"docdir = @docdir@" is lower, so things won't work as
expected.

Autoconf only obeys GNU Coding Standards here, so if
you are not willing to change the name of the variable
to resolve the problem, you have to wrestle with GCS.

Previously reported here:
http://bugzilla.gnome.org/show_bug.cgi?id=316508