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.h

@@ -370,7 +370,7 @@ int git_config_rename(const char *var, const char *value);
 #define DIFF_PICKAXE_IGNORE_CASE	32
 
 void diffcore_std(struct diff_options *);
-void diffcore_fix_diff_index(struct diff_options *);
+void diffcore_fix_diff_index(void);
 
 #define COMMON_DIFF_OPTIONS_HELP \
 "\ncommon diff options:\n" \