fusefs handlers are processed on behalf of the non-rt fusefs server
thread, which never holds rt locks by design while issuing memory
management calls (e.g. collect_wait_list()). So there is no need to
pull memory from the private real-time allocator which storage may be
limited, plain malloc is fine.

At this chance, add a few missing __STD() notations to existing free()
calls paired with __STD(malloc()).