message: win32 only: fix detection of obfs4proxy.exe
diff: #include "addrman.h"
  #include "ui_interface.h"
  #include <sys/stat.h>
  +#include <boost/dll.hpp>
  #ifdef WIN32
  #include <string.h>
  @@ -1601,7 +1602,8 @@ static void run_tor() {
  boost::optional<std::string> clientTransportPlugin;
  struct stat sb;
  #ifdef WIN32
  - if (stat("obfs4proxy.exe", &sb) == 0 && sb.st_mode & S_IXUSR) {
  + fs::path obfs4proxy_file = dll::program_location().parent_path() / "obfs4proxy.exe";
  + if (boost::filesystem::exists(obfs4proxy_file)) {
  clientTransportPlugin = "obfs4 exec obfs4proxy.exe";
  }
  #else
  