Reduce code size when mbedtls_x509_*_info() unused

Introduce MBEDTLS_X509_INFO to indicate the availability of the
mbedtls_x509_*_info() function and closely related APIs. When this is
not defined, also omit name and description from
mbedtls_oid_descriptor_t, and omit OID arrays, macros, and types that
are entirely unused. This saves several KB of code space.

Change-Id: I056312613379890e0d70e1d08c34171287c0aa17
diff --git a/library/version_features.c b/library/version_features.c
index fc0b1f8..a1beb13 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -540,6 +540,9 @@
 #if defined(MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE)
     "MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE",
 #endif /* MBEDTLS_X509_CHECK_EXTENDED_KEY_USAGE */
+#if defined(MBEDTLS_X509_INFO)
+    "MBEDTLS_X509_INFO",
+#endif /* MBEDTLS_X509_INFO */
 #if defined(MBEDTLS_X509_RSASSA_PSS_SUPPORT)
     "MBEDTLS_X509_RSASSA_PSS_SUPPORT",
 #endif /* MBEDTLS_X509_RSASSA_PSS_SUPPORT */