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/transaction.c b/openbsc/src/transaction.c
index 5e55665..8e2b0b6 100644
--- a/openbsc/src/transaction.c
+++ b/openbsc/src/transaction.c
@@ -29,7 +29,7 @@
#include <openbsc/mncc.h>
#include <openbsc/paging.h>
-static void *tall_trans_ctx;
+void *tall_trans_ctx;
void _gsm48_cc_trans_free(struct gsm_trans *trans);