Depend on docbook-dtds for local validation

Added Requires: docbook-dtds to the gnome-doc-utils-stylesheets subpackage
so that xsltproc validation wouldn't have to download DTDs.

Koji has no network access so this was resulting in xsltproc warnings:
> warning: failed to load external entity "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"

gnome-doc-utils.spec

@@ -4,7 +4,7 @@
 
 Name: gnome-doc-utils
 Version: 0.20.10
-Release: 1%{?dist}
+Release: 2%{?dist}
 License: GPLv2+ and LGPLv2+ and GFDL
 Group: Development/Tools
 Summary: Documentation utilities for GNOME
@@ -53,6 +53,8 @@ all auxiliary files in your source tree.
 Summary: XSL stylesheets used by gnome-doc-utils
 License: LGPLv2+
 Group: Development/Tools
+# for the validation with xsltproc to use local dtds
+Requires: docbook-dtds
 # for /usr/share/pkgconfig
 Requires: pkgconfig
 # for /usr/share/xml
@@ -94,6 +96,9 @@ sed -i -e '/^Requires:/d' $RPM_BUILD_ROOT%{_datadir}/pkgconfig/xml2po.pc
 %{_datadir}/xml/mallard
 
 %changelog
+* Wed Apr 18 2012 Kalev Lember <kalevlember@gmail.com> - 0.20.10-2
+- Depend on docbook-dtds for local validation
+
 * Mon Mar 26 2012 Matthew Barnes <mbarnes@redhat.com> - 0.20.10-1
 - Update to 0.20.10 (needed for evolution-3.4.0)