move to libcommon-cs: gsm48_create_mm_serv_rej(), gsm48_create_loc_upd_rej()

Used by libbsc, libmsc as well as osmo-bsc and osmo-bsc_nat.

Moving gsm48_create* to libcommon-cs affects linking of osmo-bsc_nat, resulting in
undefined references to gsm48_extract_mi() and gsm48_paging_extract_mi(); fix
that by placing libfilter.a left of libbsc.a upon linker invocation.

Change-Id: I212c2567b56191022b683674c1c4daf842839946
diff --git a/openbsc/src/osmo-bsc_nat/Makefile.am b/openbsc/src/osmo-bsc_nat/Makefile.am
index 141b892..be33d28 100644
--- a/openbsc/src/osmo-bsc_nat/Makefile.am
+++ b/openbsc/src/osmo-bsc_nat/Makefile.am
@@ -41,11 +41,11 @@
 
 osmo_bsc_nat_LDADD = \
 	$(top_builddir)/src/libmgcp/libmgcp.a \
+	$(top_builddir)/src/libfilter/libfilter.a \
 	$(top_builddir)/src/libbsc/libbsc.a \
 	$(top_builddir)/src/libcommon-cs/libcommon-cs.a \
 	$(top_builddir)/src/libtrau/libtrau.a \
 	$(top_builddir)/src/libcommon/libcommon.a \
-	$(top_builddir)/src/libfilter/libfilter.a \
 	$(LIBOSMOSCCP_LIBS) \
 	$(LIBOSMOCORE_LIBS) \
 	$(LIBOSMOGSM_LIBS) \