gnome-desktop: add --disable-desktop-docs

autobuilder logs show the below failure:

| xsltproc -o lgpl-vi.omf --stringparam db2omf.basename lgpl --stringparam
db2omf.format 'docbook' --stringparam db2omf.dtd "-//OASIS//DTD DocBook XML
V4.1.2//EN" --stringparam db2omf.lang vi --stringparam db2omf.omf_dir
"/usr/share/omf" --stringparam db2omf.help_dir "/usr/share/gnome/help"
--stringparam db2omf.omf_in ...
| http://www.oasis-open.org/docbook/xml/4.1.2/dbpoolx.mod:632: parser warning :
PEReference: %notation.class; not found
| ...
| unable to parse oc/lgpl.xml
| make[3]: *** [lgpl-oc.omf] Error 1

However this issue can't be reproduced in my Ubuntu 9.04 system. I suppose
it's because on autobuilder the newer libxml has a stricter syntax requirement
about the related xml files.

Actually before commit b8b13dcbb7 upgraded
gnome-desktop to 2.32.1, we also didn't build desktop-docs. The commit removed
no-desktop-docs.patch but didn't notice the Makefile.am depends on
--disable-desktop-docs to decice whether desktop-docs will be built.

So we should continue to make sure desktop-docs is not built.

Fixes [BUGID: 587]

Signed-off-by: Dexuan Cui <dexuan.cui@intel.com>

meta/recipes-gnome/gnome/gnome-desktop.inc

@@ -3,7 +3,7 @@ SECTION = "x11/gnome"
 LICENSE = "GPLv2 & LGPLv2"
 DEPENDS = "gconf-dbus libxrandr virtual/libx11 gtk+ glib-2.0 gnome-doc-utils"
 
-EXTRA_OECONF = "--disable-scrollkeeper"
+EXTRA_OECONF = "--disable-scrollkeeper --disable-desktop-docs"
 
 do_configure_prepend () {
 	cp ${STAGING_DATADIR}/gnome-common/data/omf.make ${S}
@@ -11,4 +11,7 @@ do_configure_prepend () {
 
 FILES_${PN} += "${datadir}/gnome-about"
 
-inherit gnome pkgconfig
+PR = "r1"
+
+inherit gnome pkgconfig
+