switch to libosmocore multihread-logging

When osmo-remsim was originally developed, libosmocore logging was
not yet thread-safe.  This meant that the worker threads of remsim-bankd
and remsim-server could not log via the libosmocore logging framework
but directly used stderr/stdout, which produced rather inconsistent log
output.

However, since 1.3.0, libosmocore has received support for
multi-threaded applications.  Let's make use of this and consistently
use it in remsim-server and remsim-bankd.  This obviously also means
adding some more log categories.

Change-Id: I7bd5264c559b756927046563a2d00c54826bee9b
diff --git a/src/bankd/bankd_main.c b/src/bankd/bankd_main.c
index 3842b0c..5b70b88 100644
--- a/src/bankd/bankd_main.c
+++ b/src/bankd/bankd_main.c
@@ -80,6 +80,8 @@
 	log_set_print_category(osmo_stderr_target, 1);
 	log_set_print_category_hex(osmo_stderr_target, 0);
 	osmo_fsm_log_addr(0);
+	log_set_print_tid(osmo_stderr_target, 1);
+	log_enable_multithread();
 
 	asn_debug = 0;