tests: Initialize log system to fix crash, update test result

Use osmo_init_logging to initialize the log system to fix crashes
when we attempt to parse broken ASN1 messages.

Ignore stderr with parse errors, update the test result. make check
is now passing.
diff --git a/tests/ussd/ussd_test.c b/tests/ussd/ussd_test.c
index 6d2a8c9..55384f1 100644
--- a/tests/ussd/ussd_test.c
+++ b/tests/ussd/ussd_test.c
@@ -19,6 +19,8 @@
  *
  */
 
+#include <osmocom/core/application.h>
+#include <osmocom/core/logging.h>
 #include <osmocom/gsm/gsm0480.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -64,12 +66,16 @@
 	return rc;
 }
 
+struct log_info info = {};
+
 int main(int argc, char **argv)
 {
 	struct ussd_request req;
 	const int size = sizeof(ussd_request);
 	int i;
 
+	osmo_init_logging(&info);
+
 	gsm0480_decode_ussd_request((struct gsm48_hdr *) ussd_request, size, &req);
 	printf("Tested if it still works. Text was: %s\n", req.text);