OS400/makefile.sh: fix shellcheck warning SC2038

Also:
- OS400/makefile.sh: use end-of-options marker in xargs command.
- OS400/make-tests.sh: drop warning suppression.
  Seems to not trigger anymore as of shellcheck 0.11.0

Closes #19451

packages/OS400/make-tests.sh

@@ -58,7 +58,7 @@ build_all_programs()
 
                 for FLAG in ${PGMCFLAGS}
                 do      case "${FLAG}" in
-                        -D?*)   # shellcheck disable=SC2001
+                        -D?*)
                                 DEFINE="$(echo "${FLAG}" | sed 's/^..//')"
                                 PGMDFNS="${PGMDFNS} '${DEFINE}'"
                                 ;;

packages/OS400/makefile.sh

@@ -35,8 +35,7 @@ cd "${TOPDIR}" || exit 1
 
 #       Make sure all files are UTF8-encoded.
 
-# shellcheck disable=SC2038
-find "${TOPDIR}" -type f -print | xargs ls -S | while read -r CCSID FILE
+find "${TOPDIR}" -type f -print0 | xargs -0 ls -S -- | while read -r CCSID FILE
 do      if [ "${CCSID}" != 1208 ]
         then    CMD="CPY OBJ('${FILE}') TOOBJ('${FILE}') FROMCCSID(*OBJ)"
                 CMD="${CMD} TOCCSID(1208) DTAFMT(*TEXT) REPLACE(*YES)"