Add missing ext/libxml dependency to ext/xmlwriter (#14327)

This adds the libxml extension to required dependencies for xmlwriter
during the configuration phase (PHP_ADD_EXTENSION_DEP) and the runtime
(ZEND_MOD_REQUIRED).

The libxml is technically not a required extension in this case but
it necessary to make it work properly (i.e. have proper error
reporting, etc.). Added due to prior libxml requirement in
documentation and build system.

ext/xmlwriter/config.m4

@@ -5,14 +5,10 @@ PHP_ARG_ENABLE([xmlwriter],
   [yes])
 
 if test "$PHP_XMLWRITER" != "no"; then
-
-  if test "$PHP_LIBXML" = "no"; then
-    AC_MSG_ERROR([XMLWriter extension requires LIBXML extension, add --with-libxml])
-  fi
-
   PHP_SETUP_LIBXML(XMLWRITER_SHARED_LIBADD, [
     AC_DEFINE(HAVE_XMLWRITER,1,[ ])
     PHP_NEW_EXTENSION(xmlwriter, php_xmlwriter.c, $ext_shared)
+    PHP_ADD_EXTENSION_DEP(xmlwriter, libxml)
     PHP_SUBST(XMLWRITER_SHARED_LIBADD)
   ])
 fi

ext/xmlwriter/php_xmlwriter.c

@@ -175,9 +175,15 @@ static char *_xmlwriter_get_valid_file_path(char *source, char *resolved_path, i
 }
 /* }}} */
 
+static const zend_module_dep xmlwriter_deps[] = {
+	ZEND_MOD_REQUIRED("libxml")
+	ZEND_MOD_END
+};
+
 /* {{{ xmlwriter_module_entry */
 zend_module_entry xmlwriter_module_entry = {
-	STANDARD_MODULE_HEADER,
+	STANDARD_MODULE_HEADER_EX, NULL,
+	xmlwriter_deps,
 	"xmlwriter",
 	ext_functions,
 	PHP_MINIT(xmlwriter),