A better fix for bug#21303

* src/w32uniscribe.c (_WIN32_WINNT): Define to 0x0600.  This is a
cleaner fix for Bug#21260 than the previous change.

src/w32uniscribe.c

@@ -18,22 +18,15 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 
 #include <config.h>
-/* Override API version - Uniscribe is only available as standard since
-   Windows 2000, though most users of older systems will have it
+/* Override API version - Uniscribe is only available as standard
+   since Windows 2000, though most users of older systems will have it
    since it installs with Internet Explorer 5.0 and other software.
-   We only enable the feature if it is available, so there is no chance
-   of calling non-existent functions.  */
+   Also, MinGW64 w32api headers by default define OPENTYPE_TAG typedef
+   only if _WIN32_WINNT >= 0x0600.  We only use the affected APIs if
+   they are available, so there is no chance of calling non-existent
+   functions.  */
 #undef _WIN32_WINNT
-#define _WIN32_WINNT 0x500
-/* MinGW64 w32api headers by default define OPENTYPE_TAG typedef only
-   if _WIN32_WINNT >= 0x0600; defining UNISCRIBE_OPENTYPE as below
-   makes that typedef visible even for lower values of _WIN32_WINNT.
-   Mingw.org's w32api headers don't use UNISCRIBE_OPENTYPE at all, and
-   the OPENTYPE_TAG typedef is defined unconditionally there.  */
-#ifdef UNISCRIBE_OPENTYPE
-# undef UNISCRIBE_OPENTYPE
-#endif
-#define UNISCRIBE_OPENTYPE 0x0100
+#define _WIN32_WINNT 0x0600
 #include <windows.h>
 #include <usp10.h>