remove nblibs, going to be superceded by src-netbsd

diff --git a/nblibs b/nblibs
deleted file mode 160000 (submodule)
index 16a3b17..0000000
--- a/nblibs
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 16a3b1767c7ccde28d1238003046dcca1fcf018c