[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/evil_diamond_runme.php

@@ -0,0 +1,16 @@
+<?php
+
+require "tests.php";
+require "evil_diamond.php";
+
+check::classes(array("evil_diamond","foo","bar","baz","spam"));
+check::functions("test");
+check::is_a("bar","foo");
+check::is_a("baz","foo");
+check::is_a("spam","foo");
+check::is_a("spam","bar");
+//No multiple inheritance
+//check::is_a("spam","baz");
+
+check::done();
+?>