[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/li_std_string_runme.php

@@ -0,0 +1,31 @@
+<?php
+
+require "tests.php";
+require "li_std_string.php";
+
+// Global variables
+//$s="initial string";
+//check::equal(GlobalString2_get() ,"global string 2", "GlobalString2 test 1");
+
+// Global variables
+$s = "initial string";
+check::equal(GlobalString2_get(), "global string 2", "GlobalString2 test 1");
+GlobalString2_set($s);
+check::equal(GlobalString2_get(), $s, "GlobalString2 test 2");
+check::equal(ConstGlobalString_get(), "const global string", "ConstGlobalString test");
+
+// Member variables
+$myStructure = new Structure();
+check::equal($myStructure->MemberString2, "member string 2", "MemberString2 test 1");
+$myStructure->MemberString2 = $s;
+check::equal($myStructure->MemberString2, $s, "MemberString2 test 2");
+check::equal($myStructure->ConstMemberString, "const member string", "ConstMemberString test");
+
+check::equal(Structure::StaticMemberString2(), "static member string 2", "StaticMemberString2 test 1");
+Structure::StaticMemberString2($s);
+check::equal(Structure::StaticMemberString2(), $s, "StaticMemberString2 test 2");
+// below broken ?
+//check::equal(Structure::ConstStaticMemberString(), "const static member string", "ConstStaticMemberString test");
+
+check::done();
+?>