[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/php5/disown/runme.php

@@ -0,0 +1,49 @@
+<?php
+
+# This file illustrates the low-level C++ interface
+# created by SWIG.  In this case, all of our C++ classes
+# get converted into function calls.
+
+require("example.php");
+
+# ----- Object creation -----
+
+print "Creating some objects:\n";
+$c = new Circle(10);
+print "    Created circle \$c\n";
+$s = new Square(10);
+print "    Created square \$s\n";
+
+# ----- Create the ShapeContainer ----
+
+$container = new ShapeContainer();
+
+$container->addShape($c);
+$container->addShape($s);
+
+# ----- Access a static member -----
+
+print "\nA total of " . Shape::nshapes() . " shapes were created\n";
+
+# ----- Delete by the old references -----
+# This should not truely delete the shapes because they are now owned
+# by the ShapeContainer.
+
+print "Delete the old references.";
+
+# Note: this invokes the virtual destructor
+$c = NULL;
+$s = NULL;
+
+print "\nA total of " . Shape::nshapes() . " shapes remain\n";
+
+# ----- Delete by the container -----
+# This should truely delete the shapes
+
+print "Delete the container.";
+$container = NULL;
+print "\nA total of " . Shape::nshapes() . " shapes remain\n";
+
+print "Goodbye\n";
+
+?>