patch 8.2.0711: temp directory might be cleared

Problem:    With a long running Vim the temp directory might be cleared on
            some systems.
Solution:   Lock the temp directory. (closes #6044)
diff --git a/src/config.h.in b/src/config.h.in
index de53ffb..5c8c7e5 100644
--- a/src/config.h.in
+++ b/src/config.h.in
@@ -484,5 +484,11 @@
 /* Define if we have isnan() */
 #undef HAVE_ISNAN
 
+/* Define if we have dirfd() */
+#undef HAVE_DIRFD
+
+/* Define if we have flock() */
+#undef HAVE_FLOCK
+
 /* Define to inline symbol or empty */
 #undef inline