Squish: Avoid crash

Due to high frequency of re-usage of the processes we may clash
with the destruction of a formerly running process using the same
QtcProcess object. Explicitly closing it before (re)starting
cleanly destructs the former process.

Change-Id: Id26e55ac3aaf5c24178d168c6391ae0c51139684
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/squish/squishtools.cpp

@@ -369,8 +369,12 @@ void SquishTools::startSquishServer(Request request)
 
     const QStringList arguments = serverArgumentsFromSettings();
     m_serverProcess.setCommand({toolsSettings.serverPath, arguments});
+
     m_serverProcess.setEnvironment(squishEnvironment());
 
+    // especially when writing server config we re-use the process fast and start the server
+    // several times and may crash as the process may not have been cleanly destructed yet
+    m_serverProcess.close();
     setState(ServerStarting);
     m_serverProcess.start();
     if (!m_serverProcess.waitForStarted()) {