[openssl/openssl] b4934a: Add an EVP demo for key encoding using EC

[faramir-dev]

  Branch: refs/heads/openssl-3.0
  Home:   https://github.com/openssl/openssl
  Commit: b4934a9533a1cf290f7f967edf5cfc028967778d
      https://github.com/openssl/openssl/commit/b4934a9533a1cf290f7f967edf5cfc028967778d
  Author: Daniel Fiala <daniel at openssl.org>
  Date:   2022-09-09 (Fri, 09 Sep 2022)

  Changed paths:
    A demos/encode/Makefile
    A demos/encode/ec_encode.c

  Log Message:
  -----------
  Add an EVP demo for key encoding using EC

Fixes openssl#14117

Reviewed-by: Tomas Mraz <tomas at openssl.org>
Reviewed-by: Matt Caswell <matt at openssl.org>
Reviewed-by: Paul Dale <pauli at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19143)

(cherry picked from commit a4b7136ebfd154636f607c50aaeec778a75b2d26)