Properly terminate server on timeouts

Do a proper cleanup when one of the termination timeouts trigger
rather than just exiting on the spot. This makes sure we don't leave
stray stuff around, e.g. unix socket files.
diff --git a/unix/x0vncserver/XDesktop.cxx b/unix/x0vncserver/XDesktop.cxx
index 9a047c8..3e67fad 100644
--- a/unix/x0vncserver/XDesktop.cxx
+++ b/unix/x0vncserver/XDesktop.cxx
@@ -19,6 +19,8 @@
  */
 
 #include <assert.h>
+#include <signal.h>
+#include <unistd.h>
 
 #include <rfb/LogWriter.h>
 
@@ -273,6 +275,10 @@
   pb = 0;
 }
 
+void XDesktop::terminate() {
+  kill(getpid(), SIGTERM);
+}
+
 bool XDesktop::isRunning() {
   return running;
 }
diff --git a/unix/x0vncserver/XDesktop.h b/unix/x0vncserver/XDesktop.h
index 7d06061..3e85aac 100644
--- a/unix/x0vncserver/XDesktop.h
+++ b/unix/x0vncserver/XDesktop.h
@@ -49,6 +49,7 @@
   // -=- SDesktop interface
   virtual void start(rfb::VNCServer* vs);
   virtual void stop();
+  virtual void terminate();
   bool isRunning();
   virtual void queryConnection(network::Socket* sock,
                                const char* userName);