heirloom-mailx: add libressl support patch

heirloom-mailx has two small issues when compiling against LibreSSL:
  - RAND_egd is used (LibreSSL does not support RAND_egd)
    Solution: "Guard" the code calling RAND_egd

  - SSLv3_client_method function is used (LibreSSL does not support SSLv3)
    Solution: "Guard" the code with #ifndef OPENSSL_NO_SSL3

Signed-off-by: Adam Duskett <Adamduskett@outlook.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>