dbus-glib: needs expat

Even though dbus can use libxml2 for XML support, dbus-glib cannot -
So make sure expat is available.

package/dbus-glib/Config.in

@@ -2,6 +2,7 @@ config BR2_PACKAGE_DBUS_GLIB
 	bool "dbus-glib"
 	depends on BR2_PACKAGE_DBUS
 	select BR2_PACKAGE_LIBGLIB2
+	select BR2_PACKAGE_EXPAT
 	help
 	  GLib bindings for D-Bus.
 

package/dbus-glib/dbus-glib.mk

@@ -23,7 +23,7 @@ DBUS_GLIB_CONF_OPT = --localstatedir=/var \
 		--disable-doxygen-docs \
 		--enable-asserts=yes
 
-DBUS_GLIB_DEPENDENCIES = uclibc host-pkgconfig dbus host-dbus host-dbus-glib libglib2
+DBUS_GLIB_DEPENDENCIES = uclibc host-pkgconfig dbus host-dbus host-dbus-glib libglib2 expat
 
 $(eval $(call AUTOTARGETS,package,dbus-glib))