[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/class_ignore_runme.php

@@ -0,0 +1,16 @@
+<?php
+
+require "tests.php";
+require "class_ignore.php";
+
+check::functions(array(do_blah,new_bar,bar_blah,new_boo,boo_away,new_far,new_hoo));
+check::classes(array(class_ignore,Bar,Boo,Far,Hoo));
+// No new vars
+check::globals(array());
+
+$bar=new bar();
+do_blah($bar);
+check::classparent($bar,"");
+
+check::done();
+?>