Add orig_commit.
Solaris does not have qsort_r
Merge pull request #2034 from jacquesg/solaris-qsort

Solaris doesn't have qsort_r either
Handle git_buf's from users more liberally
Merge pull request #2036 from ethomson/git_buf_sanitize

Handle git_buf's from users more liberally
Add orig & final commit test.
Merge pull request #2033 from xtao/blame_orig_commit

Add orig_commit.