copyright years breaking sync with automake

[Karl Berry]

The following files are/were all synced from automake.  They had their
copyright years unified in gnulib.  But not in automake.  Can this be
resolved one way or another, please?

   build-aux/ar-lib
   build-aux/compile
   build-aux/depcomp
   build-aux/elisp-comp
   build-aux/mdate-sh
   build-aux/missing
   build-aux/ylwrap

karl