++libgit2
API changes.
Merge pull request #324 from libgit2/bump-libgit2

Bump libgit2
Added a status flag for GIT_STATUS_OPT_RENAMES_FROM_REWRITES.
Merge pull request #325 from libgit2/renames-from-rewrites

Added a status flag for GIT_STATUS_OPT_RENAMES_FROM_REWRITES.
Index entries could be NULL.
Merge pull request #326 from libgit2/null-index-entries

Index entries could be NULL.