message: platform_posix: add support for Haiku
diff: // Copyright 2017-2018 ccls Authors
  // SPDX-License-Identifier: Apache-2.0
  -#if defined(__unix__) || defined(__APPLE__)
  +#if defined(__unix__) || defined(__APPLE__) || defined(__HAIKU__)
  #include "platform.hh"
  #include "utils.hh"
  