message: HostThreadPosix::Cancel: remove android-specific implementation
  Noone is calling this function on android, so we can just use the
  generic llvm_unreachable "implementation".
diff: @@ -41,14 +41,11 @@ Status HostThreadPosix::Join(lldb::thread_result_t *result) {
  Status HostThreadPosix::Cancel() {
  Status error;
  if (IsJoinable()) {
  -#ifndef __ANDROID__
  #ifndef __FreeBSD__
  llvm_unreachable("someone is calling HostThread::Cancel()");
  -#endif
  +#else
  int err = ::pthread_cancel(m_thread);
  error.SetError(err, eErrorTypePOSIX);
  -#else
  - error.SetErrorString("HostThreadPosix::Cancel() not supported on Android");
  #endif
  }
  return error;
  