- (dtucker) [configure.ac kex.c key.c myproposal.h] Test for the presence of
   NID_X9_62_prime256v1, NID_secp384r1 and NID_secp521r1 and test that the
   latter actually works before using it.  Fedora (at least) has NID_secp521r1
   that doesn't work (see https://bugzilla.redhat.com/show_bug.cgi?id=1021897).
 - (dtucker) [configure.ac] Fix brackets in NID_secp521r1 test.
 - (dtucker) [configure.ac] Add missing "test".
 - (dtucker) [key.c] Check for the correct defines for NID_secp521r1.