Return the write size

Amends 535d312e93

Change-Id: Icdc0eec0d017a65b64b6c20233c67caf2e81c16a
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/libs/utils/launchersocket.cpp

@@ -343,6 +343,7 @@ qint64 LauncherHandle::write(const QByteArray &data)
     WritePacket p(m_token);
     p.inputData = data;
     sendPacket(p);
+    return data.size();
 }
 
 // Ensure it's called from caller's thread, after moving LauncherHandle into the launcher's thread