sgsn_rim: Add routing for (GERAN) BSSGP RIM messages

The SGSN currently does not forward BSSGP RIM messages.

Related: SYS#5103
Depends: libosmocore Icd667f41d5735de56cd9fb257670337c679dd258
Change-Id: I6fde8ab8955660b48000ca1b650cfc7c7b2e24ba
diff --git a/src/sgsn/Makefile.am b/src/sgsn/Makefile.am
index 6a7392b..8738986 100644
--- a/src/sgsn/Makefile.am
+++ b/src/sgsn/Makefile.am
@@ -62,6 +62,7 @@
 	sgsn_auth.c \
 	gprs_subscriber.c \
 	sgsn_cdr.c \
+	sgsn_rim.c \
 	slhc.c \
 	gprs_llc_xid.c \
 	v42bis.c \