remote: provide read access to the callback structure

This should make it easier for bindings to dynamically override their
own callbacks.

include/git2/remote.h

@@ -519,6 +519,17 @@ GIT_EXTERN(int) git_remote_init_callbacks(
  */
 GIT_EXTERN(int) git_remote_set_callbacks(git_remote *remote, const git_remote_callbacks *callbacks);
 
+/**
+ * Retrieve the current callback structure
+ *
+ * This provides read access to the callbacks structure as the remote
+ * sees it.
+ *
+ * @param remote the remote to query
+ * @return a pointer to the callbacks structure
+ */
+GIT_EXTERN(const git_remote_callbacks *) git_remote_get_callbacks(git_remote *remote);
+
 /**
  * Get the statistics structure that is filled in by the fetch operation.
  */

src/remote.c

@@ -1253,6 +1253,13 @@ int git_remote_set_callbacks(git_remote *remote, const git_remote_callbacks *cal
 	return 0;
 }
 
+const git_remote_callbacks *git_remote_get_callbacks(git_remote *remote)
+{
+	assert(remote);
+
+	return &remote->callbacks;
+}
+
 int git_remote_set_transport(git_remote *remote, git_transport *transport)
 {
 	assert(remote && transport);