Add some gnulib.modules

Add some gnulib.modules

* gnulib.modules: Add errno, limits-h, safe-read, sys_stat.
Not sure about the relationship between gnulib.modules
and paxutils/gnulib.modules, but anyway tar itself uses
these so we should depend on them.  (Perhaps it would be
better if there was just one Gnulib module list for tar;
that would be less confusing.)