remove libs/ldns/install-sh as it's being auto-generated

libs/.gitignore

@@ -887,7 +887,6 @@ missing
 !/ldns/drill/install-sh
 !/ldns/examples/config.h.in
 !/ldns/examples/configure
-!/ldns/install-sh
 !/ldns/ldns/config.h.in
 !/libdingaling/config.guess
 !/libdingaling/config.sub