[PHP] Add support for PHP7.

PHP5's C extension API has changed substantially so you need to use
-php7 to specify you want PHP7 compatible wrappers.
Fixes https://github.com/swig/swig/issues/571

Examples/test-suite/php5/conversion_ns_template_runme.php

@@ -0,0 +1,10 @@
+<?php
+
+require "tests.php";
+require "conversion_ns_template.php";
+
+check::classes(array("conversion_ns_template","Foo_One","Bar_One","Hi"));
+// this is too hard, I'm not sure what to test for,
+
+check::done();
+?>