[dovecot/core] d31a40: lib-compression: use LZ4_compress_default if can

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/dovecot/core
  Commit: d31a407872fb93f907fc2587daaa780ffa9a6f56
      https://github.com/dovecot/core/commit/d31a407872fb93f907fc2587daaa780ffa9a6f56
  Author: Martti Rannanjärvi <martti.rannanjarvi at dovecot.fi>
  Date:   2016-12-27 (Tue, 27 Dec 2016)

  Changed paths:
    M m4/want_lz4.m4
    M src/lib-compression/ostream-lz4.c

  Log Message:
  -----------
  lib-compression: use LZ4_compress_default if can

LZ4_compress is deprecated.