[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/virtual_vs_nonvirtual_base_runme.php

@@ -0,0 +1,11 @@
+<? 
+
+require "tests.php";
+require "virtual_vs_nonvirtual_base.php";
+
+$fail = new SimpleClassFail();
+$work = new SimpleClassWork();
+
+check::equal($work->getInner()->get(), $fail->getInner()->get(), "should both be 10");
+
+?>