osmo_io: Add osmo_io_get_ioops() function

This function can be used by user code to obtain the currently-set io
operations, it's the inverse of osmo_io_set_ioops().

Change-Id: I03398c811b9534f50c6644b21eea89a04be29fb0
diff --git a/src/core/libosmocore.map b/src/core/libosmocore.map
index a50a9ed..72a6038 100644
--- a/src/core/libosmocore.map
+++ b/src/core/libosmocore.map
@@ -258,6 +258,7 @@
 osmo_iofd_close;
 osmo_iofd_free;
 osmo_iofd_get_data;
+osmo_iofd_get_ioops;
 osmo_iofd_get_fd;
 osmo_iofd_get_name;
 osmo_iofd_set_name;