Port to GCC-8

[Bernhard Voelker]

[PATCH 1/2] xargs.c: port to GCC 8
[PATCH 2/2] oldfind.c: port to GCC 8

Pushed at
  https://git.sv.gnu.org/cgit/findutils.git/commit/?id=371b3017f8

Have a nice day,
Berny