PHP: handle -prefix when checking if a class has been subclassed or not

git-svn-id: https://swig.svn.sourceforge.net/svnroot/swig/trunk@11637 626c5289-ae23-0410-ae9c-e8d60b6d4f22
diff --git a/Source/Modules/php.cxx b/Source/Modules/php.cxx
index bae922e..eee4d1f 100644
--- a/Source/Modules/php.cxx
+++ b/Source/Modules/php.cxx
@@ -1636,7 +1636,7 @@
 	} else {
 	  Node *parent = Swig_methodclass(n);
 	  String *classname = Swig_class_name(parent);
-	  Printf(output, "\t\tif (get_class($this) === '%s') {\n", classname);
+	  Printf(output, "\t\tif (get_class($this) === '%s%s') {\n", prefix, classname);
 	  Printf(output, "\t\t\t$_this = null;\n");
 	  Printf(output, "\t\t} else {\n");
 	  Printf(output, "\t\t\t$_this = $this;\n");