Add missing S_ISREG definitions for VS2022
Otherwise building with VS2022 fails with: ``` Creating library D:/temp/29/.sw/out/323969/gnome.glib.gio-2.71.0.lib and object D:/temp/29/.sw/out/323969/gnome.glib.gio-2.71.0.exp xdgmime.c.4b279509.obj : error LNK2019: unresolved external symbol S_ISREG referenced in function _gio_xdg_get_mime_type_for_file xdgmimecache.c.79af418f.obj : error LNK2001: unresolved external symbol S_ISREG D:\temp\29\.sw\out\323969\gnome.glib.gio-2.71.0.dll : fatal error LNK1120: 1 unresolved externals ``` See https://gitlab.gnome.org/GNOME/glib/-/issues/2560 Signed-off-by: Philip Withnall <pwithnall@endlessos.org>