sh-quote: backport fix from diffutils * lib/sh-quote.c (init_sh_quoting_options): Use C89 through C17 style for parameterless static function. This avoided a warning when compiling diffutils. This patch is backported from a circa-2009 diffutils patch and lets us remove diffutils/gl/lib/sh-quote.c.diff; see: https://git.savannah.gnu.org/cgit/diffutils.git/commit/?id=8c3d25a63a2c5912170ef6e13f748f3904e6b5cf