Add certificate policy of type any policy id

Add a function for getting the certificate policy. Currently only
"Any Policy" is supported.

include/mbedtls/oid.h

@@ -167,6 +167,11 @@
 #define MBEDTLS_OID_INIHIBIT_ANYPOLICY          MBEDTLS_OID_ID_CE "\x36" /**< id-ce-inhibitAnyPolicy OBJECT IDENTIFIER ::=  { id-ce 54 } */
 #define MBEDTLS_OID_FRESHEST_CRL                MBEDTLS_OID_ID_CE "\x2E" /**< id-ce-freshestCRL OBJECT IDENTIFIER ::=  { id-ce 46 } */
 
+/*
+ * Certificate policies
+ */
+#define MBEDTLS_OID_ANY_POLICY              MBEDTLS_OID_CERTIFICATE_POLICIES "\x00" /**< anyPolicy OBJECT IDENTIFIER ::= { id-ce-certificatePolicies 0 } */
+
 /*
  * Netscape certificate extensions
  */
@@ -576,6 +581,16 @@ int mbedtls_oid_get_md_hmac( const mbedtls_asn1_buf *oid, mbedtls_md_type_t *md_
  */
 int mbedtls_oid_get_extended_key_usage( const mbedtls_asn1_buf *oid, const char **desc );
 
+/**
+ * \brief          Translate certificate policies OID into description
+ *
+ * \param oid      OID to use
+ * \param desc     place to store string pointer
+ *
+ * \return         0 if successful, or MBEDTLS_ERR_OID_NOT_FOUND
+ */
+int mbedtls_oid_get_certificate_policies( const mbedtls_asn1_buf *oid, const char **desc );
+
 /**
  * \brief          Translate md_type into hash algorithm OID
  *