MinGW updates.

* js/mingw-full-version-in-resources:
  mingw: include the full version information in the resources

This fixes https://github.com/git-for-windows/git/issues/723

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Introduce a new "oidmap" API and rewrite oidset to use it.

* jt/oidmap:
  oidmap: map with OID as key

Operations that do not touch (majority of) packed refs have been
optimized by making accesses to packed-refs file lazy; we no longer
pre-parse everything, and an access to a single ref in the
packed-refs does not touch majority of irrelevant refs, either.

* mh/mmap-packed-refs: (21 commits)
  packed-backend.c: rename a bunch of things and update comments
  mmapped_ref_iterator: inline into `packed_ref_iterator`
  ref_cache: remove support for storing peeled values
  packed_ref_store: get rid of the `ref_cache` entirely
  ref_store: implement `refs_peel_ref()` generically
  packed_read_raw_ref(): read the reference from the mmapped buffer
  packed_ref_iterator_begin(): iterate using `mmapped_ref_iterator`
  read_packed_refs(): ensure that references are ordered when read
  packed_ref_cache: keep the `packed-refs` file mmapped if possible
  packed-backend.c: reorder some definitions
  mmapped_ref_iterator_advance(): no peeled value for broken refs
  mmapped_ref_iterator: add iterator over a packed-refs file
  packed_ref_cache: remember the file-wide peeling state
  read_packed_refs(): read references with minimal copying
  read_packed_refs(): make parsing of the header line more robust
  read_packed_refs(): only check for a header at the top of the file
  read_packed_refs(): use mmap to read the `packed-refs` file
  die_unterminated_line(), die_invalid_line(): new functions
  packed_ref_cache: add a backlink to the associated `packed_ref_store`
  prefix_ref_iterator: break when we leave the prefix
  ...

This is similar to using the hashmap in hashmap.c, but with an
easier-to-use API. In particular, custom entry comparisons no longer
need to be written, and lookups can be done without constructing a
temporary entry structure.

This is implemented as a thin wrapper over the hashmap API. In
particular, this means that there is an additional 4-byte overhead due
to the fact that the first 4 bytes of the hash is redundantly stored.
For now, I'm taking the simpler approach, but if need be, we can
reimplement oidmap without affecting the callers significantly.

oidset has been updated to use oidmap.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Keep a copy of the `packed-refs` file contents in memory for as long
as a `packed_ref_cache` object is in use:

* If the system allows it, keep the `packed-refs` file mmapped.

* If not (either because the system doesn't support `mmap()` at all,
  or because a file that is currently mmapped cannot be replaced via
  `rename()`), then make a copy of the file's contents in
  heap-allocated space, and keep that around instead.

We base the choice of behavior on a new build-time switch,
`MMAP_PREVENTS_DELETE`. By default, this switch is set for Windows
variants.

After this commit, `MMAP_NONE` and `MMAP_TEMPORARY` are still handled
identically. But the next commit will introduce a difference.

This whole change is still pointless, because we only read the
`packed-refs` file contents immediately after instantiating the
`packed_ref_cache`. But that will soon change.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

"make style" runs git-clang-format to help developers by pointing
out coding style issues.

* bw/git-clang-format:
  Makefile: add style build rule
  clang-format: outline the git project's coding style

Many of our programs consider that it is OK to release dynamic
storage that is used throughout the life of the program by simply
exiting, but this makes it harder to leak detection tools to avoid
reporting false positives.  Plug many existing leaks and introduce
a mechanism for developers to mark that the region of memory
pointed by a pointer is not lost/leaking to help these tools.

* jk/leak-checkers:
  add UNLEAK annotation for reducing leak false positives
  set_git_dir: handle feeding gitdir to itself
  repository: free fields before overwriting them
  reset: free allocated tree buffers
  reset: make tree counting less confusing
  config: plug user_config leak
  update-index: fix cache entry leak in add_one_file()
  add: free leaked pathspec after add_files_to_cache()
  test-lib: set LSAN_OPTIONS to abort by default
  test-lib: --valgrind should not override --verbose-log

Platforms that ship with a separate sha1 with collision detection
library can link to it instead of using the copy we ship as part of
our source tree.

* ti/external-sha1dc:
  sha1dc: allow building with the external sha1dc library
  sha1dc: build git plumbing code more explicitly

Code clean-up.

* jn/vcs-svn-cleanup:
  vcs-svn: move remaining repo_tree functions to fast_export.h
  vcs-svn: remove repo_delete wrapper function
  vcs-svn: remove custom mode constants
  vcs-svn: remove more unused prototypes and declarations