Remove support for HMAC_TEST_PRIVATE_KEY_FORMAT
Remove support for HMAC_TEST_PRIVATE_KEY_FORMAT

This is a bogus, undocumented format that was intended for testing; I
don't think anyone is using it.

Reviewed-by: Richard Levitte <5fb523282dd7956571c80524edc2dccfa0bd8234@openssl.org>

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl