fix a few nits

[Jim Meyering]

Here are three tiny changes:

[PATCH 1/3] maint: fix comment grammar to placate make syntax-check
[PATCH 2/3] maint: correct a stale comment in sort.c
[PATCH 3/3] tests: reverse args in Coreutils.pm-invoked diff, for consistency

 src/remove.c       |    2 +-
 src/sort.c         |    2 +-
 tests/Coreutils.pm |    6 +++---
 3 files changed, 5 insertions(+), 5 deletions(-)