Allow wxThread::Wait() and Delete() to block, even under wxMSW.

Add "wait mode" parameter to these methods which can be used to make them
block even under wxMSW where they currently dispatch messages when called
which can be totally unexpected.

Do keep the old behaviour for compatibility however, although it will change i
3.2.

Closes #12998.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67185 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/apptbase.h

@@ -40,7 +40,7 @@ public:
 
     // wait for the handle to be signaled, return WAIT_OBJECT_0 if it is or, in
     // the GUI code, WAIT_OBJECT_0 + 1 if a Windows message arrived
-    virtual WXDWORD WaitForThread(WXHANDLE hThread) = 0;
+    virtual WXDWORD WaitForThread(WXHANDLE hThread, int flags) = 0;
 
 
 #ifndef __WXWINCE__