Remove experimental 56bit export ciphers

These ciphers are removed:
    TLS1_CK_RSA_EXPORT1024_WITH_RC4_56_MD5
    TLS1_CK_RSA_EXPORT1024_WITH_RC2_CBC_56_MD5
    TLS1_CK_RSA_EXPORT1024_WITH_DES_CBC_SHA
    TLS1_CK_DHE_DSS_EXPORT1024_WITH_DES_CBC_SHA
    TLS1_CK_RSA_EXPORT1024_WITH_RC4_56_SHA
    TLS1_CK_DHE_DSS_EXPORT1024_WITH_RC4_56_SHA
    TLS1_CK_DHE_DSS_WITH_RC4_128_SHA
They were defined in a long-expired IETF internet-draft:
draft-ietf-tls-56-bit-ciphersuites-01.txt

Reviewed-by: Richard Levitte <levitte@openssl.org>