[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/import_nomodule_runme.php

@@ -0,0 +1,20 @@
+<?php
+require "tests.php";
+require "import_nomodule.php";
+
+// No new functions
+check::functions(array(create_foo,delete_foo,test1,is_python_builtin));
+// No new classes
+check::classes(array(import_nomodule,Bar));
+// now new vars
+check::globals(array());
+
+$f = import_nomodule::create_Foo();
+import_nomodule::test1($f,42);
+import_nomodule::delete_Foo($f);
+
+$b = new Bar();
+import_nomodule::test1($b,37);
+
+check::done();
+?>