change gtk-doc.bbclass to pull in depends and oeconf

(From OE-Core rev: 28dacc5a83ccf74f8f4895adb471af703d02259a)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/gtk-doc.bbclass

@@ -1,4 +1,16 @@
-# We don't have gtk-doc so disable it
-do_configure_prepend() {
-	echo "EXTRA_DIST=">> ${S}/gtk-doc.make
-}
+# Helper class to pull in the right gtk-doc dependencies and disable
+# gtk-doc.
+#
+# Long-term it would be great if this class could be toggled between
+# gtk-doc-stub-native and the real gtk-doc-native, which would enable
+# re-generation of documentation.  For now, we'll make do with this which
+# packages up any existing documentation (so from tarball builds).
+
+DEPENDS_append = " gtk-doc-stub-native"
+DEPENDS_virtclass-native_append = " gtk-doc-stub-native"
+
+EXTRA_OECONF_append = "\
+  --disable-gtk-doc \
+  --disable-gtk-doc-html \
+  --disable-gtk-doc-pdf \
+"