Avoid pointless propagatedBuildInputs

It suffices for Perl to be in buildInputs
for json-format.pl's hashbang to get fixed up.

json-rpc-shell-master.nix

@@ -18,16 +18,13 @@ pkgs.stdenv.mkDerivation rec {
 		jansson
 		curl
 		libev
+		perl
 	] ++ lib.optionals full [
 		readline
 	] ++ lib.optionals (!full) [
 		libedit
 	];
 
-	propagatedBuildInputs = with pkgs; [
-		perl
-	];
-
 	src = if local then
 		builtins.path {
 			path = ../${pname}/git;