Include git2/odb_backend.h in git2.h Since this isn't under sys/ we need to have it included in the main git2.h file. This fixes #2551.
diff --git a/include/git2.h b/include/git2.h
index f749760..d843539 100644
--- a/include/git2.h
+++ b/include/git2.h
@@ -32,6 +32,7 @@
#include "git2/notes.h"
#include "git2/object.h"
#include "git2/odb.h"
+#include "git2/odb_backend.h"
#include "git2/oid.h"
#include "git2/pack.h"
#include "git2/patch.h"