Add well known types to php runtime. (#3697)

* Add well known types to php runtime.

* Fix php7.0 tests

* No longer generate empty.proto in test as it has been included in
runtime.

* Fix zts build

* Clean code

* Rename g_p_b_empty to empty.

* Don't generate code for empty.proto in compatibility test

* Fix 32-bit

* Fix mac build

* Fix Makefile.am to add new files

1 files changed, 23 insertions, 0 deletions

diff --git a/php/src/Google/Protobuf/NullValue.php b/php/src/Google/Protobuf/NullValue.php
new file mode 100644
index 00000000..d4022ccc
--- /dev/null
+++ b/php/src/Google/Protobuf/NullValue.php
@@ -0,0 +1,23 @@
+<?php
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: google/protobuf/struct.proto
+
+namespace Google\Protobuf;
+
+/**
+ * `NullValue` is a singleton enumeration to represent the null value for the
+ * `Value` type union.
+ *  The JSON representation for `NullValue` is JSON `null`.
+ *
+ * Protobuf enum <code>Google\Protobuf\NullValue</code>
+ */
+class NullValue
+{
+    /**
+     * Null value.
+     *
+     * Generated from protobuf enum <code>NULL_VALUE = 0;</code>
+     */
+    const NULL_VALUE = 0;
+}
+