Fix public header on sys/refs.h GIT_BEGIN/END_DECL were missing from sys/refs.h and preventing compilation with g++ as the symbol were mangled.
diff --git a/include/git2/sys/refs.h b/include/git2/sys/refs.h
index dd95ca1..d2ce2e0 100644
--- a/include/git2/sys/refs.h
+++ b/include/git2/sys/refs.h
@@ -12,6 +12,15 @@
#include "git2/oid.h"
/**
+ * @file git2/sys/refs.h
+ * @brief Low-level Git ref creation
+ * @defgroup git_backend Git custom backend APIs
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
* Create a new direct reference from an OID.
*
* @param name the reference name
@@ -35,4 +44,6 @@ GIT_EXTERN(git_reference *) git_reference__alloc_symbolic(
const char *name,
const char *target);
+/** @} */
+GIT_END_DECL
#endif