Use Unicode command line when not using wmain() under Windows

While we use wmain() for the compilers that provide it since the changes of
bfa78c63b9, we still didn't handle Unicode
command line arguments not representable in the current Windows code page
correctly when using other compilers (e.g. MinGW).

Now use Win32 ::GetCommandLine() function for them and parse the command line
ourselves instead of relying on non-Unicode-friendly main() arguments which
can't represent arbitrary Unicode strings when not using UTF-8 (which is never
the case under Windows).

src/msw/main.cpp

@@ -194,8 +194,6 @@ int wxEntry(int& argc, wxChar **argv)
 
 #endif // wxUSE_BASE
 
-#if wxUSE_GUI
-
 // ----------------------------------------------------------------------------
 // Windows-specific wxEntry
 // ----------------------------------------------------------------------------
@@ -204,8 +202,17 @@ struct wxMSWCommandLineArguments
 {
     wxMSWCommandLineArguments() { argc = 0; argv = NULL; }
 
-    void Init(const wxArrayString& args)
+    // Initialize this object from the current process command line.
+    void Init()
     {
+        // Get the command line.
+        const wxChar* const cmdLine = ::GetCommandLine();
+        if ( !cmdLine )
+            return;
+
+        // And tokenize it.
+        const wxArrayString args = wxCmdLineParser::ConvertStringToArgs(cmdLine);
+
         argc = args.size();
 
         // +1 here for the terminating NULL
@@ -239,6 +246,8 @@ struct wxMSWCommandLineArguments
 
 static wxMSWCommandLineArguments wxArgs;
 
+#if wxUSE_GUI
+
 // common part of wxMSW-specific wxEntryStart() and wxEntry() overloads
 static bool
 wxMSWEntryCommon(HINSTANCE hInstance, int nCmdShow)
@@ -249,20 +258,7 @@ wxMSWEntryCommon(HINSTANCE hInstance, int nCmdShow)
     wxApp::m_nCmdShow = nCmdShow;
 #endif
 
-    // parse the command line: we can't use pCmdLine in Unicode build so it is
-    // simpler to never use it at all (this also results in a more correct
-    // argv[0])
-
-    // break the command line in words
-    wxArrayString args;
-
-    const wxChar *cmdLine = ::GetCommandLine();
-    if ( cmdLine )
-    {
-        args = wxCmdLineParser::ConvertStringToArgs(cmdLine);
-    }
-
-    wxArgs.Init(args);
+    wxArgs.Init();
 
     return true;
 }
@@ -289,7 +285,16 @@ WXDLLEXPORT int wxEntry(HINSTANCE hInstance,
     return wxEntry(wxArgs.argc, wxArgs.argv);
 }
 
-#endif // wxUSE_GUI
+#else // !wxUSE_GUI
+
+int wxEntry()
+{
+    wxArgs.Init();
+
+    return wxEntry(wxArgs.argc, wxArgs.argv);
+}
+
+#endif // wxUSE_GUI/!wxUSE_GUI
 
 // ----------------------------------------------------------------------------
 // global HINSTANCE