Merge branch 'ps/object-file-cleanup'

Code clean-up.

* ps/object-file-cleanup:
  object-store: merge "object-store-ll.h" and "object-store.h"
  object-store: remove global array of cached objects
  object: split out functions relating to object store subsystem
  object-file: drop `index_blob_stream()`
  object-file: split up concerns of `HASH_*` flags
  object-file: split out functions relating to object store subsystem
  object-file: move `xmmap()` into "wrapper.c"
  object-file: move `git_open_cloexec()` to "compat/open.c"
  object-file: move `safe_create_leading_directories()` into "path.c"
  object-file: move `mkdir_in_gitdir()` into "path.c"

meson.build

@@ -296,6 +296,7 @@ libgit_sources = [
   'common-init.c',
   'compat/nonblock.c',
   'compat/obstack.c',
+  'compat/open.c',
   'compat/terminal.c',
   'compiler-tricks/not-constant.c',
   'config.c',
@@ -386,6 +387,7 @@ libgit_sources = [
   'object-file-convert.c',
   'object-file.c',
   'object-name.c',
+  'object-store.c',
   'object.c',
   'oid-array.c',
   'oidmap.c',