move talloc context creation out of on_dso / constructors

the various constructors get called in a non-obvious, linker determined
order, which makes certain objects disappear from the talloc report.

This change moves the talloc context creation into a new talloc_ctx.c file
diff --git a/openbsc/src/trau_mux.c b/openbsc/src/trau_mux.c
index 9ff7001..6a19f0c 100644
--- a/openbsc/src/trau_mux.c
+++ b/openbsc/src/trau_mux.c
@@ -47,7 +47,7 @@
 static LLIST_HEAD(ss_map);
 static LLIST_HEAD(ss_upqueue);
 
-static void *tall_map_ctx, *tall_upq_ctx;
+void *tall_map_ctx, *tall_upq_ctx;
 
 /* map one particular subslot to another subslot */
 int trau_mux_map(const struct gsm_e1_subslot *src,
@@ -235,12 +235,3 @@
 	return subchan_mux_enqueue(mx, dst_e1_ss->e1_ts_ss, trau_bits_out,
 				   TRAU_FRAME_BITS);
 }
-
-static __attribute__((constructor)) void on_dso_load_trau_mux(void)
-{
-	tall_map_ctx = talloc_named_const(tall_bsc_ctx, 1,
-					  "trau_map_entry");
-
-	tall_upq_ctx = talloc_named_const(tall_bsc_ctx, 1,
-					  "trau_upq_entry");
-}