Squashed 'deps/libgit2/' changes from df19219..16e7596

16e7596 Merge pull request #2447 from phkelley/pkt_assert
bc8a088 Fix assert when receiving uncommon sideband packet
0145afe Merge pull request #2445 from ethomson/checkout_conflict_test
f404626 checkout::conflict tests: only test owner mode
9c46409 Merge pull request #2444 from libgit2/phkelley/flexarray
f36d57b Fixes #2443 Zero size arrays are an extension
86cb34c Merge pull request #2442 from libgit2/cmn/leaks
c19b1c0 pack: clean up error returns
966fb20 tree: free in error conditions
5e0f47c pack: free the new pack struct if we fail to insert
c61dc1a travis: build the master branch
1fe5624 Merge pull request #2435 from ethomson/text_attr
a252b9e Merge pull request #2439 from ethomson/revert_export
4e813a8 Export git_revert_commit
d412165 Update text=auto / core.autocrlf=false behavior
e1fc03c Add CHANGELOG entry for mixed-EOL fix
3ddd0d9 Merge remote-tracking branch 'upstream/cmn/mixed-eol-passthrough'
29fe897 Add CHANGELOG entry for treebuilder map
5e37874 Merge remote-tracking branch 'upstream/cmn/treebuilder-perf'
130cb54 Add CHANGELOG entry for shared packs
5815266 Merge branch 'cmn/global-mwf'
3575715 Merge pull request #2434 from libgit2/rb/contributing-updates
5a76ad3 crlf: pass-through mixed EOL buffers from LF->CRLF
b3b66c5 Share packs across repository instances
d30447c Add a CHANGELOG entry for the filebuf change
461da57 Merge remote-tracking branch 'upstream/cmn/filebuf-atomic-unlock'
b247a39 missing paren
a142ed9 Update CONTRIBUTING and PROJECTS
28f087c libgit2 v0.21.0
1589aa0 Merge pull request #2425 from libgit2/cmn/clone-auth-change
e93206e Merge pull request #2421 from libgit2/cmn/init-ssl-once
09561d3 test: remove assembla clone test
3382d8b test: use read-only account
9c3e4e9 http: fix typo in credentials logic
081e76b ssl: init everything all the time
8f897b6 ssl: init also without threads
cf15ac8 ssl: cargo-cult thread safety
5fa0494 ssl: use locking
76f7616 remote: update documentation
1d3364a netops: init OpenSSL once under lock
3f3d21b Merge pull request #2417 from libgit2/cmn/revwalk-array-fix
f9a9766 revwalk: more sensible array handling
fcc6006 treentry: no need for manual size book-keeping
978fbb4 treebuilder: don't keep removed entries around
4d3f1f9 treebuilder: use a map instead of vector to store the entries
7064cda Merge pull request #2416 from libgit2/cmn/treebuilder-insert-sorted
17fbf85 pathspec: use C guards in header
2c11d2e treebuilder: insert sorted
281da00 remote: fix rename docs
47fae92 Merge branch 'cmn/soversion' into development
4fb32a4 Bump version to 0.21.0
9980767 Change SOVERSION at API breaks
ce5e661 Merge pull request #2407 from libgit2/cmn/remote-rename-more
9560203 Merge pull request #2409 from phkelley/win32_thread_fixes
1b4e29b React to review feedback
fb59176 Win32: Fix object::cache::threadmania test on x64
231f350 remote: don't free the remote on delete
d154456 remote: handle symrefs when renaming
eb6aa79 remote: failing test for renaming with a symref
72bca13 remote: return problem refspecs instead of using a callback
61dcfe1 remote: make sure the name stays valid on rename
5a49ff9 remote: remove rename code for anonymous remotes
e58281a filebuf: make unlocking atomic
4b0a36e Merge branch 'development'
29d7242 Merge branch 'development'

git-subtree-dir: deps/libgit2
git-subtree-split: 16e7596d78ff233c6f1aa42678fde8b946b44f4b
Merge commit 'ecdb6306dd6ad6b2fe09648cdd0adcea2cd02f7f' into jacquesg/update-libgit2
Don't include libgit2 meta files in release
Remote.xs: name() now optionally takes a list to store rename problems
Changes: update