patch 8.1.2344: Cygwin: warning for using strptime()

Problem:    Cygwin: warning for using strptime().
Solution:   Move defining _XOPEN_SOURCE and __USE_XOPEN to vim.h. (Ken Takata,
            closes #5265)  Use 700 for _XOPEN_SOURCE for mkdtemp().
diff --git a/src/version.c b/src/version.c
index 9b8a02f..9df71b8 100644
--- a/src/version.c
+++ b/src/version.c
@@ -738,6 +738,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2344,
+/**/
     2343,
 /**/
     2342,