[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/threads_exception_runme.php

@@ -0,0 +1,43 @@
+<?php
+
+require "tests.php";
+require "threads_exception.php";
+
+// Check functions
+check::functions(array(test_simple,test_message,test_hosed,test_unknown,test_multi,is_python_builtin));
+// Check classes.
+check::classes(array(Exc,Test,threads_exception));
+// Chek globals.
+check::globals(array(exc_code,exc_msg));
+
+$t = new Test();
+try {
+    $t->unknown();
+} catch (Exception $e) {
+    check::equal($e->getMessage(), 'C++ A * exception thrown', '');
+}
+
+try {
+    $t->simple();
+} catch (Exception $e) {
+    check::equal($e->getCode(), 37, '');
+}
+
+try {
+    $t->message();
+} catch (Exception $e) {
+    check::equal($e->getMessage(), 'I died.', '');
+}
+
+try {
+    $t->hosed();
+} catch (Exception $e) {
+    check::equal($e->getMessage(), 'C++ Exc exception thrown', '');
+}
+
+foreach (Array(1,2,3,4) as $i) {
+    try {
+	$t->multi($i);
+    } catch (Exception $e) {
+    }
+}