OpenSSL missing NIST p224r1

[Nathaniel McCallum]

On Fedora 21, OpenSSL doesn't appear to support NIST p224r1, but *does*
support other NIST curves. I presume this was intentional, but I'm not
sure why. Can someone enlighten me?

$ openssl ecparam -list_curves
  secp384r1 : NIST/SECG curve over a 384 bit prime field
  secp521r1 : NIST/SECG curve over a 521 bit prime field
  prime256v1: X9.62/SECG curve over a 256 bit prime field

Nathaniel