Add X509 purpose constant

X509_PURPOSE_OCSP_HELPER, X509_PURPOSE_TIMESTAMP_SIGN are available from
OpenSSL for many years:
  - X509_PURPOSE_OCSP_HELPER, since 2001
  - X509_PURPOSE_TIMESTAMP_SIGN, since 2006

Author: vjardin

ext/openssl/openssl.stub.php

@@ -49,6 +49,16 @@
  * @cvalue X509_PURPOSE_ANY
  */
 const X509_PURPOSE_ANY = UNKNOWN;
+/**
+ * @var int
+ * @cvalue X509_PURPOSE_OCSP_HELPER
+ */
+const X509_PURPOSE_OCSP_HELPER = UNKNOWN;
+/**
+ * @var int
+ * @cvalue X509_PURPOSE_TIMESTAMP_SIGN
+ */
+const X509_PURPOSE_TIMESTAMP_SIGN = UNKNOWN;
 
 /* digest algorithm constants */