Fix LyX server on Windows

On some recent Windows versions, GetLastError() may also return
NO_ERROR instead of ERROR_IO_PENDING during an overlapped write
operation to a pipe. This was confusing the state machine in
Server.cpp so that replies to commands were scheduled but were
never actually output.

(cherry picked from commit cf5f2661dc)

src/Server.cpp

@@ -356,7 +356,7 @@ bool LyXComm::pipeServer()
 
 			error = GetLastError();
 
-			if (success && error == ERROR_IO_PENDING) {
+			if (success && (error == ERROR_IO_PENDING || error == NO_ERROR)) {
 				// The write operation is still pending.
 				// We get here when a reader is started
 				// well before a reply is ready, so delay

status.23x

@@ -299,6 +299,8 @@ What's new
 - When reconfiguring LyX, correctly detect commands specified with a
   full path with spaces (bug 11214).
 
+- Fix the LyX server on Windows so that replies are actually output.
+
 
 * DOCUMENTATION AND LOCALIZATION