Build fixes

Some fixes for build environments where dependencies are installed in
distinct directories.

Change-Id: I38808fd2911747b266ee6fde91187a88dd7ae355
diff --git a/openbsc/tests/gtphub/Makefile.am b/openbsc/tests/gtphub/Makefile.am
index 137924d..5c834b7 100644
--- a/openbsc/tests/gtphub/Makefile.am
+++ b/openbsc/tests/gtphub/Makefile.am
@@ -7,6 +7,8 @@
 	-Wall \
 	-ggdb3 \
 	$(LIBOSMOCORE_CFLAGS) \
+	$(LIBOSMOABIS_CFLAGS) \
+	$(LIBGTP_CFLAGS) \
 	$(NULL)
 
 EXTRA_DIST = \
@@ -35,6 +37,6 @@
 	$(top_builddir)/src/gprs/gtphub.o \
 	$(top_builddir)/src/gprs/gprs_utils.o \
 	$(LIBOSMOCORE_LIBS) \
-	-lgtp \
+	$(LIBGTP_LIBS) \
 	-lrt \
 	$(NULL)