msc: Add includes to silence a compiler warning.
diff --git a/openbsc/src/ussd.c b/openbsc/src/ussd.c
index 3c27646..19b494f 100644
--- a/openbsc/src/ussd.c
+++ b/openbsc/src/ussd.c
@@ -33,6 +33,7 @@
 #include <openbsc/gsm_04_80.h>
 #include <openbsc/gsm_subscriber.h>
 #include <openbsc/debug.h>
+#include <openbsc/osmo_msc.h>
 
 /* Declarations of USSD strings to be recognised */
 const char USSD_TEXT_OWN_NUMBER[] = "*#100#";