RemoteLinux: Try SIGTERM first when terminating processes

This was done for the "kill by process name" operation, but not for the
"kill by PID" one.

Change-Id: Ia8eb57d1fa030624470489dbd0e7b03093fd822b
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/plugins/remotelinux/remotelinuxsignaloperation.cpp

@@ -96,7 +96,8 @@ QString RemoteLinuxSignalOperation::interruptProcessByNameCommandLine(const QStr
 
 void RemoteLinuxSignalOperation::killProcess(qint64 pid)
 {
-    run(signalProcessByPidCommandLine(pid, 9));
+    run(QString::fromLatin1("%1; %2").arg(signalProcessByPidCommandLine(pid, 15),
+                                          signalProcessByPidCommandLine(pid, 9)));
 }
 
 void RemoteLinuxSignalOperation::killProcess(const QString &filePath)