Merge branch 'mh/simplify-repack-without-refs'

"git remote update --prune" to drop many refs has been optimized.

* mh/simplify-repack-without-refs:
  sort_string_list(): rename to string_list_sort()
  prune_remote(): iterate using for_each_string_list_item()
  prune_remote(): rename local variable
  repack_without_refs(): make the refnames argument a string_list
  prune_remote(): sort delete_refs_list references en masse
  prune_remote(): initialize both delete_refs lists in a single loop
  prune_remote(): exit early if there are no stale references

diff --cc builtin/apply.c
Simple merge

diff --cc builtin/receive-pack.c
Simple merge

diff --cc builtin/repack.c
Simple merge

diff --cc connect.c
Simple merge

diff --cc notes.c
Simple merge

diff --cc refs.c
Simple merge