Extract wxLOCALE_XXX constants into their own header

No real changes, just make it possible to use these constants without
including the entire wx/intl.h.

Note that the existing headers including wx/intl.h need to keep
including it, unfortunately, as not doing it any longer would break
compilation of any code including them which relies on _() or
wxGetTranslation() being defined after including e.g. wx/dc.h. This was,
of course, never guaranteed, but in practice it worked for a very long
time, so don't break it now.

This commit is best viewed with --color-moved git option.

include/wx/localedefs.h

@@ -0,0 +1,77 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/localedefs.h
+// Purpose:     Definitions of common locale-related constants
+// Author:      Vadim Zeitlin
+// Created:     2021-07-31 (extracted from wx/intl.h)
+// Copyright:   (c) 2021 Vadim Zeitlin <vadim@wxwidgets.org>
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_LOCALEDEFS_H_
+#define _WX_LOCALEDEFS_H_
+
+// ----------------------------------------------------------------------------
+// wxLayoutDirection: used by wxWindow, wxDC etc
+// ----------------------------------------------------------------------------
+
+// Note that this one must be available even when wxUSE_INTL == 0 as it's used
+// outside of locale code too.
+
+enum wxLayoutDirection
+{
+    wxLayout_Default,
+    wxLayout_LeftToRight,
+    wxLayout_RightToLeft
+};
+
+#if wxUSE_INTL
+
+// ----------------------------------------------------------------------------
+// wxLocaleCategory: the category of locale settings
+// ----------------------------------------------------------------------------
+
+enum wxLocaleCategory
+{
+    // (any) numbers
+    wxLOCALE_CAT_NUMBER,
+
+    // date/time
+    wxLOCALE_CAT_DATE,
+
+    // monetary value
+    wxLOCALE_CAT_MONEY,
+
+    // default category for wxLocaleInfo values which only apply to a single
+    // category (e.g. wxLOCALE_SHORT_DATE_FMT)
+    wxLOCALE_CAT_DEFAULT,
+
+    wxLOCALE_CAT_MAX
+};
+
+// ----------------------------------------------------------------------------
+// wxLocaleInfo: the items understood by wxLocale::GetInfo()
+// ----------------------------------------------------------------------------
+
+enum wxLocaleInfo
+{
+    // the thousands separator (for wxLOCALE_CAT_NUMBER or MONEY)
+    wxLOCALE_THOUSANDS_SEP,
+
+    // the character used as decimal point (for wxLOCALE_CAT_NUMBER or MONEY)
+    wxLOCALE_DECIMAL_POINT,
+
+    // the stftime()-formats used for short/long date and time representations
+    // (under some platforms short and long date formats are the same)
+    //
+    // NB: these elements should appear in this order, code in GetInfo() relies
+    //     on it
+    wxLOCALE_SHORT_DATE_FMT,
+    wxLOCALE_LONG_DATE_FMT,
+    wxLOCALE_DATE_TIME_FMT,
+    wxLOCALE_TIME_FMT
+
+};
+
+#endif // wxUSE_INTL
+
+#endif // _WX_LOCALEDEFS_H_