patch 8.1.2347: MacOS: build fails
Problem: MacOS: build fails.
Solution: Don't define _XOPEN_SOURCE for Mac.
diff --git a/src/vim.h b/src/vim.h
index c53b141..9b49ba1 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -36,7 +36,7 @@
Error: configure did not run properly. Check auto/config.log.
# endif
-# ifdef UNIX
+# if defined(UNIX) && !defined(MACOS_X)
// 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.