Merge branch 'tb/enable-cruft-packs-by-default'

When "gc" needs to retain unreachable objects, packing them into
cruft packs (instead of exploding them into loose object files) has
been offered as a more efficient option for some time.  Now the use
of cruft packs has been made the default and no longer considered
an experimental feature.

* tb/enable-cruft-packs-by-default:
  repository.h: drop unused `gc_cruft_packs`
  builtin/gc.c: make `gc.cruftPacks` enabled by default
  t/t9300-fast-import.sh: prepare for `gc --cruft` by default
  t/t6500-gc.sh: add additional test cases
  t/t6500-gc.sh: refactor cruft pack tests
  t/t6501-freshen-objects.sh: prepare for `gc --cruft` by default
  t/t5304-prune.sh: prepare for `gc --cruft` by default
  builtin/gc.c: ignore cruft packs with `--keep-largest-pack`
  builtin/repack.c: fix incorrect reference to '-C'
  pack-write.c: plug a leak in stage_tmp_packfiles()

diff --cc builtin/gc.c
Simple merge

diff --cc builtin/repack.c
Simple merge

diff --cc pack-write.c
index 381555359cd0da022a377423b2cb01efa6b7ab6a,4da0ccc5f50181d2db677394ae31ebed19ca4876..3b3ce89de6e9c2f13b81ca6b67c9a3b02cee54e3
--- 1/pack-write.c
--- 2/pack-write.c
+++ b/pack-write.c
@@@ -571,7 -569,7 +571,8 @@@ void stage_tmp_packfiles(struct strbuf 
        if (mtimes_tmp_name)
                rename_tmp_packfile(name_buffer, mtimes_tmp_name, "mtimes");
  
 +      free((char *)rev_tmp_name);
+       free(mtimes_tmp_name);
  }
  
  void write_promisor_file(const char *promisor_name, struct ref **sought, int nr_sought)

diff --cc repo-settings.c
Simple merge

diff --cc repository.h
Simple merge