filefrag: fix GCC7.x compiler warning

../../misc/filefrag.c:591:33: warning: comparison between pointer and
zero character constant [-Wpointer-compare]
  for (cpp = argv + optind; *cpp != '\0'; cpp++) {

Signed-off-by: Marc Thomas <marc@dragonfly.plus.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
1 file changed