message: Fixed build on FreeBSD
diff: #include <errno.h>
  #include <io.h>
  #include <stdio.h>
  -#elif defined __linux__ || defined __APPLE__ || defined __HAIKU__
  +#elif defined __linux__ || defined __APPLE__ || defined __HAIKU__ || defined __FreeBSD__
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  @@ -178,7 +178,7 @@ cv::String getcwd()
  sz = GetCurrentDirectoryA((DWORD)buf.size(), buf.data());
  return cv::String(buf.data(), (size_t)sz);
  #endif
  -#elif defined __linux__ || defined __APPLE__ || defined __HAIKU__
  +#elif defined __linux__ || defined __APPLE__ || defined __HAIKU__ || defined __FreeBSD__
  for(;;)
  {
  char* p = ::getcwd(buf.data(), buf.size());
  @@ -212,7 +212,7 @@ bool createDirectory(const cv::String& path)
  #else
  int result = _mkdir(path.c_str());
  #endif
  -#elif defined __linux__ || defined __APPLE__ || defined __HAIKU__
  +#elif defined __linux__ || defined __APPLE__ || defined __HAIKU__ || defined __FreeBSD__
  int result = mkdir(path.c_str(), 0777);
  #else
  int result = -1;
  @@ -327,7 +327,7 @@ private:
  Impl& operator=(const Impl&); // disabled
  };
  -#elif defined __linux__ || defined __APPLE__ || defined __HAIKU__
  +#elif defined __linux__ || defined __APPLE__ || defined __HAIKU__ || defined __FreeBSD__
  struct FileLock::Impl
  {
  @@ -441,7 +441,7 @@ cv::String getCacheDirectory(const char* sub_directory_name, const char* configu
  default_cache_path = "/tmp/";
  CV_LOG_WARNING(NULL, "Using world accessible cache directory. This may be not secure: " << default_cache_path);
  }
  -#elif defined __linux__ || defined __HAIKU__
  +#elif defined __linux__ || defined __HAIKU__ || defined __FreeBSD__
  // https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
  if (default_cache_path.empty())
  {
  