Add wxModule::AreInitialized()

This internal function will be useful to check if the modules are
already initialized, i.e. if the library is in the "steady state"
between the end of the initialization and the beginning of the cleanup
phases.

tests/misc/module.cpp

@@ -15,6 +15,8 @@
 #include "wx/module.h"
 #include "wx/wxcrt.h"       // for wxStrcat()
 
+static bool gs_wasInitialized = wxModule::AreInitialized();
+
 // ----------------------------------------------------------------------------
 // test classes derived from wxModule
 // ----------------------------------------------------------------------------
@@ -89,6 +91,12 @@ ModuleD::ModuleD()
 // tests themselves
 // ----------------------------------------------------------------------------
 
+TEST_CASE("wxModule::Initialized", "[module]")
+{
+    CHECK( !gs_wasInitialized );
+    CHECK( wxModule::AreInitialized() );
+}
+
 TEST_CASE("wxModule::LoadOrder", "[module]")
 {
     // module D is the only one with no dependencies and so should load as first (and so on):