Fix breakage introduced in commit a8b3b09d

The order of the calls to “ctx.use_privatekey” and “ctx.use_certificate”
was wrong, leading to an exception being thrown.

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>

lib/utils/x509.py

@@ -334,7 +334,7 @@ def PrepareX509CertKeyCheck(cert, key):
 
   """
   ctx = OpenSSL.SSL.Context(OpenSSL.SSL.TLSv1_METHOD)
-  ctx.use_certificate(cert)
   ctx.use_privatekey(key)
+  ctx.use_certificate(cert)
 
   return ctx.check_privatekey