RequestHandler::Disable(join = false) is problematic

...as it causes ~RequestHandler to be called with mIpcThread still running,
triggering the assert in ~RequestHandler and keeping the thread potentially
still running during exit.

The odd SalMainPipeExchangeSignal_impl acting upong just SIGTERM (instead of
turning off the IPC thread early for each invocation of LO's signal handler,
say) is effectively like that ever since
ee3351d7 "#89023# splash screen optimization";
just change it to use RequestHandler::SetDowning instead.

Change-Id: I238476706c2463130a6ede64a062d46af953ba6f

desktop/source/app/officeipcthread.cxx

@@ -300,7 +300,7 @@ void ImplPostProcessDocumentsEvent( ProcessDocumentsRequest* pEvent )
 oslSignalAction SAL_CALL SalMainPipeExchangeSignal_impl(void* /*pData*/, oslSignalInfo* pInfo)
 {
     if( pInfo->Signal == osl_Signal_Terminate )
-        RequestHandler::Disable(false);
+        RequestHandler::SetDowning();
     return osl_Signal_ActCallNextHdl;
 }
 
@@ -879,7 +879,7 @@ RequestHandler::Status PipeIpcThread::enable(rtl::Reference<IpcThread> * thread)
     }
 }
 
-void RequestHandler::Disable(bool join)
+void RequestHandler::Disable()
 {
     osl::ClearableMutexGuard aMutex( GetMutex() );
 
@@ -899,7 +899,7 @@ void RequestHandler::Disable(bool join)
         handler->cReady.set();
 
         // exit gracefully and join
-        if (join && handler->mIpcThread.is())
+        if (handler->mIpcThread.is())
         {
             handler->mIpcThread->join();
             handler->mIpcThread.clear();

desktop/source/app/officeipcthread.hxx

@@ -120,7 +120,7 @@ class RequestHandler: public salhelper::SimpleReferenceObject
 
     // return sal_False if second office
     static Status               Enable(bool ipc);
-    static void                 Disable(bool join = true);
+    static void                 Disable();
     // start dispatching events...
     static void                 SetReady();
     static void                 WaitForReady();