tests: use 'check_PROGRAMS' instead of 'noinst_PROGRAMS'

When using 'check_PROGRAMS', autoconf/automake generates smarter
Makefiles, so that the test programs are not being compiled during
the normal 'make all', but only during 'make check'.

Change-Id: I9b60429c8c3922dd97809c72ed7960ffdc059d8b
diff --git a/tests/smlc_subscr/Makefile.am b/tests/smlc_subscr/Makefile.am
index 9ed3b59..61a601f 100644
--- a/tests/smlc_subscr/Makefile.am
+++ b/tests/smlc_subscr/Makefile.am
@@ -20,7 +20,7 @@
 	smlc_subscr_test.err \
 	$(NULL)
 
-noinst_PROGRAMS = \
+check_PROGRAMS = \
 	smlc_subscr_test \
 	$(NULL)