add .tar.tstamp files to year and top levels

These `.tar.tstamp` files will be used, along with the entry
`.tar.tstamp` files, to form compressed tarballs that
can be reproduced exactly the same way, down to the byte,
under both macOS and Linux.

Stay tuned ... :-)

2014/.filelist

@@ -8,4 +8,5 @@
 2014/Makefile
 2014/README.md
 2014/rules.txt
+2014/.tar.tstamp
 2014/.year