osmo_io: Add iofd_handle_recv()

Handle msg reception in a common function that can be called from the
different backends.

Change-Id: Ifc407d446805f885d37767f421ff710cb276a01f
diff --git a/src/core/osmo_io_internal.h b/src/core/osmo_io_internal.h
index d45b161..0f0465d 100644
--- a/src/core/osmo_io_internal.h
+++ b/src/core/osmo_io_internal.h
@@ -133,6 +133,7 @@
 struct msgb *iofd_msgb_pending(struct osmo_io_fd *iofd);
 struct msgb *iofd_msgb_pending_or_alloc(struct osmo_io_fd *iofd);
 
+void iofd_handle_recv(struct osmo_io_fd *iofd, struct msgb *msg, int rc, struct iofd_msghdr *msghdr);
 void iofd_handle_segmented_read(struct osmo_io_fd *iofd, struct msgb *msg, int rc);
 
 int iofd_txqueue_enqueue(struct osmo_io_fd *iofd, struct iofd_msghdr *msghdr);