message: avoid crash on alphine linux
diff: #include <stdio.h>
  #include <dirent.h>
  #include <errno.h>
  +#include <limits.h>
  #include "sha1.h"
  namespace ardb
  @@ -414,11 +415,12 @@ namespace ardb
  int real_path(const std::string& path, std::string& real_path)
  {
  - char* tmp = realpath(path.c_str(), NULL);
  + char buf[PATH_MAX + 1];
  + char* tmp = realpath(path.c_str(), buf);
  if (NULL != tmp)
  {
  real_path.assign(tmp);
  - free(tmp);
  + //free(tmp);
  return 0;
  }
  return errno;
  