php: fix WDDX extension build failure

Fix WDDX extension build failure.
The documentation and source are conflicting about this, in theory
libexpat support is deprecated and libxml2 can replace it, but it seems
not so for WDDX, so pull in expat for it.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/php/Config.ext

@@ -310,6 +310,7 @@ config BR2_PACKAGE_PHP_EXT_SIMPLEXML
 
 config BR2_PACKAGE_PHP_EXT_WDDX
 	bool "WDDX"
+	select BR2_PACKAGE_EXPAT
 	select BR2_PACKAGE_PHP_EXT_LIBXML2
 	help
 	  WDDX support

package/php/php.mk

@@ -38,7 +38,6 @@ PHP_CONF_OPT += $(if $(BR2_PACKAGE_PHP_EXT_SOCKETS),--enable-sockets) \
 		$(if $(BR2_PACKAGE_PHP_EXT_DOM),--enable-dom) \
 		$(if $(BR2_PACKAGE_PHP_EXT_SIMPLEXML),--enable-simplexml) \
 		$(if $(BR2_PACKAGE_PHP_EXT_SOAP),--enable-soap) \
-		$(if $(BR2_PACKAGE_PHP_EXT_WDDX),--enable-wddx) \
 		$(if $(BR2_PACKAGE_PHP_EXT_XML),--enable-xml) \
 		$(if $(BR2_PACKAGE_PHP_EXT_XMLREADER),--enable-xmlreader) \
 		$(if $(BR2_PACKAGE_PHP_EXT_XMLWRITER),--enable-xmlwriter) \
@@ -68,6 +67,11 @@ ifeq ($(BR2_PACKAGE_PHP_EXT_LIBXML2),y)
 	PHP_DEPENDENCIES += libxml2
 endif
 
+ifeq ($(BR2_PACKAGE_PHP_EXT_WDDX),y)
+	PHP_CONF_OPT += --enable-wddx --with-libexpat-dir=$(STAGING_DIR)/usr
+	PHP_DEPENDENCIES += expat
+endif
+
 ifeq ($(BR2_PACKAGE_PHP_EXT_XMLRPC),y)
 	PHP_CONF_OPT += --with-xmlrpc \
 		$(if $(BR2_PACKAGE_LIBICONV),--with-iconv-dir=$(STAGING_DIR)/usr)