Delphi pipe client may fail even in a non-error condition

In TPipeStreamBase.ReadDirect(), the code performs a peek on the pipe. If no data is available (bytes = 0), GetLastError is still checked, even though Microsoft documentation clearly states that not all functions set the last error code to 0 on success (https://msdn.microsoft.com/en-us/library/windows/desktop/ms679360(v=vs.85).aspx). Furthermore, because PeekNamedPipe only mentions that GetLastError should be called on failure, the logic of the if test must be changed.