Win32: use Wide Chars APIs

configure.ac

@@ -207,6 +207,8 @@ case "${host_os}" in
     AC_CHECK_TOOL(OBJCOPY, objcopy, :)
     AC_DEFINE([_WIN32_WINNT], 0x0502, [Define to '0x0502' for Windows XP SP2 APIs.])
     AC_DEFINE([_WIN32_IE], 0x0600, [Define to '0x0600' for IE 6.0 (and shell) APIs.])
+    AC_DEFINE([_UNICODE], [1], [Define to 1 for Unicode (Wide Chars) APIs.])
+    AC_DEFINE([UNICODE], [1], [Define to 1 for Unicode (Wide Chars) APIs.])
 
     case "${host_os}" in
       *mingw32*)