tests: make --disable-bgpd kill bgpd tests too

bgpd tests don't compile or run with --disable-bgpd, let's catch this in
the Makefile.

Reported-by: Joachim Nilsson <troglobit@gmail.com>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/tests/Makefile.am b/tests/Makefile.am
index cd6b2f1..7bc880b 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -4,9 +4,15 @@
 AM_CFLAGS = $(PICFLAGS)
 AM_LDFLAGS = $(PILDFLAGS)
 
+if BGPD
+TESTS_BGPD = aspathtest testbgpcap ecommtest testbgpmpattr testbgpmpath
+else
+TESTS_BGPD =
+endif
+
 noinst_PROGRAMS = testsig testbuffer testmemory heavy heavywq heavythread \
-		aspathtest testprivs teststream testbgpcap ecommtest \
-		testbgpmpattr testchecksum testbgpmpath tabletest
+		testprivs teststream testchecksum tabletest \
+		$(TESTS_BGPD)
 
 testsig_SOURCES = test-sig.c
 testbuffer_SOURCES = test-buffer.c