snapcraft: Fix missing files in "make dist" target

Signed-off-by: Martin Winter <mwinter@opensourcerouting.org>

snapcraft/Makefile.am

@@ -1,25 +1,7 @@
 EXTRA_DIST = snapcraft.yaml \
 	README.snap_build.md \
 	README.usage.md \
-	scripts/Makefile \
-	scripts/bgpd-service \
-	scripts/isisd-service \
-	scripts/ldpd-service \
-	scripts/ospf6d-service \
-	scripts/ospfd-service \
-	scripts/pimd-service \
-	scripts/ripd-service \
-	scripts/ripngd-service \
-	scripts/zebra-service \
-	defaults/bgpd.conf.default \
-	defaults/isisd.conf.default \
-	defaults/ldpd.conf.default \
-	defaults/ospf6d.conf.default \
-	defaults/ospfd.conf.default \
-	defaults/pimd.conf.default \
-	defaults/ripd.conf.default \
-	defaults/ripngd.conf.default \
-	defaults/vtysh.conf.default \
-	defaults/zebra.conf.default \
+	scripts \
+	defaults \
 	helpers \
 	snap