patch 9.1.0203: build-error on GNU/Hurd

Problem:  build-error on GNU HURD
Solution: Define _XOPEN_SOURCE like for Android and Cygwin
          (James McCoy)

strptime() requires _XOPEN_SOURCE to be defined for its declaration to
be visible.  This is already done for non-Android Linux and Cygwin, but
also needs to be exposed for GNU/Hurd.

closes: #14285

Signed-off-by: James McCoy <jamessan@jamessan.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    203,
 /**/
     202,
 /**/

src/vim.h

@@ -36,7 +36,7 @@
 #  error configure did not run properly.  Check auto/config.log.
 # endif
 
-# if (defined(__linux__) && !defined(__ANDROID__)) || defined(__CYGWIN__)
+# if (defined(__linux__) && !defined(__ANDROID__)) || defined(__CYGWIN__) || defined(__GNU__)
 // Needed for strptime().  Needs to be done early, since header files can
 // include other header files and end up including time.h, where these symbols
 // matter for Vim.