Do away at autconf checking of HAVE_EVP_SHA256 AND HAVE_EVP_SHA1 methods.

At autoconfigure/compile time the availability of sha256 and sha1 are checked. However this is not necessary as compilation will succeed without problems without these methods. They are just string arguments to be passed, and the and the availability could just be checked by inspecting the return code, whether it is a failure due to unavailability, or otherwise.
It could in fact be that sha256 can even be considered standard.