Fix for PCH-less build of wxProtocol after recent changes.

Include wx/app.h in protocol.cpp, don't include it in http.cpp which doesn't
need it any more.

See #17031.

src/common/http.cpp

@@ -22,7 +22,6 @@
 
 #ifndef WX_PRECOMP
     #include "wx/string.h"
-    #include "wx/app.h"
 #endif
 
 #include "wx/tokenzr.h"

src/common/protocol.cpp

@@ -21,6 +21,7 @@
 #include "wx/protocol/log.h"
 
 #ifndef WX_PRECOMP
+    #include "wx/app.h"
     #include "wx/module.h"
 #endif