Compile fix

Remove unneeded closeWriteChannel().

Amends d22505c41f

Change-Id: I499039f2c46d70473a4b1a2c89ad6b2c27174f3a
Reviewed-by: hjk <hjk@qt.io>

tests/manual/process/main.cpp

@@ -53,7 +53,6 @@ static int testSynchronous(const QString &cmd, const QStringList &args)
     p.start();
     if (!p.waitForStarted())
         return -2;
-    p.closeWriteChannel();
 
     QByteArray stdOut;
     QByteArray stdErr;