Merge branch 'jk/unused-anno-more'

More UNUSED annotation to help using -Wunused option with the
compiler.

* jk/unused-anno-more:
  ll-merge: mark unused parameters in callbacks
  diffcore-pickaxe: mark unused parameters in pickaxe functions
  convert: mark unused parameter in null stream filter
  apply: mark unused parameters in noop error/warning routine
  apply: mark unused parameters in handlers
  date: mark unused parameters in handler functions
  string-list: mark unused callback parameters
  object-file: mark unused parameters in hash_unknown functions
  mark unused parameters in trivial compat functions
  update-index: drop unused argc from do_reupdate()
  submodule--helper: drop unused argc from module_list_compute()
  diffstat_consume(): assert non-zero length

diff --cc archive.c
Simple merge

diff --cc builtin/gc.c
Simple merge

diff --cc builtin/remote.c
Simple merge

diff --cc git-compat-util.h
Simple merge

diff --cc merge-ort.c
Simple merge

diff --cc object-file.c
Simple merge