Makefile: Build gtp-{link,tunnel} by default, but don't install them

They used to be in check_programs, but then this would only build them
during 'make check' which not everyone knows or is using.

Change-Id: Idd2b3a66e5968686e6bbff59dbc89b7673def8dd
Inspired-by: Thomas Boros <tomas.boros92@gmail.com>
diff --git a/tools/Makefile.am b/tools/Makefile.am
index 95aef86..ec2eb66 100644
--- a/tools/Makefile.am
+++ b/tools/Makefile.am
@@ -1,7 +1,7 @@
 include $(top_srcdir)/Make_global.am
 
-check_PROGRAMS = gtp-link		\
-		 gtp-tunnel
+noinst_PROGRAMS = gtp-link		\
+		  gtp-tunnel
 
 gtp_link_SOURCES = gtp-link.c
 gtp_link_LDADD = ../src/libgtpnl.la ${LIBMNL_LIBS}