Fix incompatbilities with MS-Windows 2000 and older

* src/w32.c <multiByteToWideCharFlags>: New global variable.
(filename_to_utf16, filename_from_ansi, check_windows_init_file):
Use it instead of the literal MB_ERR_INVALID_CHARS.
(maybe_load_unicows_dll): Initialize multiByteToWideCharFlags as
appropriate for the underlying OS version.  For details, see
http://lists.gnu.org/archive/html/emacs-devel/2016-01/msg00835.html.
* src/w32.h: Declare multiByteToWideCharFlags.
* src/w32fns.c (Fx_file_dialog, Fw32_shell_execute)
(add_tray_notification): Use multiByteToWideCharFlags instead of
the literal MB_ERR_INVALID_CHARS.
(_resetstkoflw_proc): New typedef.
(w32_reset_stack_overflow_guard): Call _resetstkoflw via a
pointer, as this function is absent in msvcrt.dll shipped with W2K
and older systems.

Copyright-paperwork-exempt: yes

1 files changed, 1 insertions, 0 deletions

diff --git a/src/w32.h b/src/w32.h
index ba3fec8b7e6..fde3803c739 100644
--- a/src/w32.h
+++ b/src/w32.h
@@ -183,6 +183,7 @@ typedef int (WINAPI *MultiByteToWideChar_Proc)(UINT,DWORD,LPCSTR,int,LPWSTR,int)
 typedef int (WINAPI *WideCharToMultiByte_Proc)(UINT,DWORD,LPCWSTR,int,LPSTR,int,LPCSTR,LPBOOL);
 extern MultiByteToWideChar_Proc pMultiByteToWideChar;
 extern WideCharToMultiByte_Proc pWideCharToMultiByte;
+extern DWORD multiByteToWideCharFlags;
 
 extern void init_environment (char **);
 extern void check_windows_init_file (void);