QAbstractSocket: make build with debug statements compile

Otherwise we would get
qabstractsocket.cpp:2224:24: error: unknown escape sequence: '\c' [-Werror]

Change-Id: I757ff2aa1c46bbba7f0c0b93f49c2f9d84927b19
Reviewed-by: Richard J. Moore <rich@kde.org>

src/network/socket/qabstractsocket.cpp

@@ -2192,7 +2192,7 @@ bool QAbstractSocket::waitForBytesWritten(int msecs)
         if (readyToWrite) {
             if (d->canWriteNotification()) {
 #if defined (QABSTRACTSOCKET_DEBUG)
-                qDebug("QAbstractSocket::waitForBytesWritten returns \c true");
+                qDebug("QAbstractSocket::waitForBytesWritten returns true");
 #endif
                 return true;
             }