Update to 1.4.3
    
    - New upstream release 1.4.3
      - compression: add support for zlib@openssh.com
      - sftp_read: return error if a too large package arrives
      - libssh2_hostkey_hash.3: update the description of return value
      - Fixed MSVC NMakefile
      - examples: use stderr for messages, stdout for data
      - openssl: do not leak memory when handling errors
      - improved handling of disabled MD5 algorithm in OpenSSL
      - known_hosts: Fail when parsing unknown keys in known_hosts file
      - configure: gcrypt doesn't come with pkg-config support
      - session_free: wrong variable used for keeping state
      - libssh2_userauth_publickey_fromfile_ex.3: mention publickey == NULL
      - comp_method_zlib_decomp: handle Z_BUF_ERROR when inflating
    - Drop upstreamed patches