Merge branch 'jk/unused-params'

Code clean-up.

* jk/unused-params:
ref-filter: drop unused "sz" parameters
ref-filter: drop unused "obj" parameters
ref-filter: drop unused buf/sz pairs
files-backend: drop refs parameter from split_symref_update()
pack-objects: drop unused parameter from oe_map_new_pack()
merge-recursive: drop several unused parameters
diff: drop complete_rewrite parameter from run_external_diff()
diff: drop unused emit data parameter from sane_truncate_line()
diff: drop unused color reset parameters
diff: drop options parameter from diffcore_fix_diff_index()

diff --cc diff.c
Simple merge

diff --cc diff.h
Simple merge