Move the include Makefile.tests to the bottom of Makefile.am(s)

The Makefile.tests was modifying global AM_CFLAGS and LDADD and could
accidentally pull /usr/include to be listed before the internal
libraries, which is known to cause problems if the headers from the
previous version of BIND 9 has been installed on the build machine.

lib/irs/tests/Makefile.am

@@ -1,5 +1,4 @@
 include $(top_srcdir)/Makefile.top
-include $(top_srcdir)/Makefile.tests
 
 AM_CPPFLAGS +=			\
 	$(LIBISC_CFLAGS)	\
@@ -9,13 +8,9 @@ LDADD +=			\
 	$(LIBISC_LIBS)		\
 	$(LIBIRS_LIBS)
 
-check_PROGRAMS = \
+check_PROGRAMS =		\
 	resconf_test
 
-TESTS = $(check_PROGRAMS)
-
-unit-local: check
-
 EXTRA_DIST = testdata
 
-LOG_COMPILER = $(builddir)/../../unit-test-driver.sh
+include $(top_srcdir)/Makefile.tests