Fixed WINCE linking error in QProcess

The error was introduced with
28ee554b37

Change-Id: If3e51227af3880496ef2da3a18835b36d65bad78
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>

src/corelib/io/qprocess_wince.cpp

@@ -233,6 +233,11 @@ bool QProcessPrivate::waitForStarted(int)
     return false;
 }
 
+bool QProcessPrivate::drainOutputPipes()
+{
+    return true;
+}
+
 bool QProcessPrivate::waitForReadyRead(int msecs)
 {
     return false;