QLocalSocket/Win: do not emit error() when no error actually occurred

This fixes a regression in 4d0c4b9.
Previously the error string was set if the error is not
ERROR_PIPE_NOT_CONNECTED but the commit changed this behaviour to set
the error string if it is ERROR_PIPE_NOT_CONNECTED.

Task-number: QTBUG-13646
Merge-request: 941
Reviewed-by: Joerg Bornemann <[email protected]>

Author: net147

src/network/socket/qlocalsocket_win.cpp

@@ -322,9 +322,9 @@ bool QLocalSocketPrivate::completeAsyncRead()
             // buffer. We will read the remaining data in the next call.
             break;
         case ERROR_PIPE_NOT_CONNECTED:
-            setErrorString(QLatin1String("QLocalSocketPrivate::completeAsyncRead"));
-            // fall through
+            return false;
         default:
+            setErrorString(QLatin1String("QLocalSocketPrivate::completeAsyncRead"));
             return false;
         }
     }