PCH build fix when building with Clang 12

Clang 12 has added a template parameter as "CALLBACK",
which conflicts with the Windows "CALLBACK" define.

Change-Id: I773899d103dcb1a852b555a1900b2de4acb6d96f
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/coreplugin/progressmanager/progressmanager_win.cpp

@@ -41,6 +41,7 @@
 
 // for windows progress bar
 #ifndef __GNUC__
+#    define CALLBACK WINAPI
 #    include <shobjidl.h>
 #endif
 

src/plugins/debugger/registerpostmortemaction.cpp

@@ -31,6 +31,7 @@
 #include <QDir>
 #include <QString>
 
+#define CALLBACK WINAPI
 #include <windows.h>
 #include <objbase.h>
 #include <shellapi.h>