librest: propagate dependencies listed in Required

These are listed in the pkg-config file so we need to propagate them for them to be found.

Also split outputs to avoid dev outputs of propagated dependencies in the closure.

pkgs/development/libraries/librest/default.nix

@@ -4,6 +4,7 @@
 , pkg-config
 , glib
 , libsoup
+, libxml2
 , gobject-introspection
 , gnome
 }:
@@ -12,6 +13,8 @@ stdenv.mkDerivation rec {
   pname = "rest";
   version = "0.8.1";
 
+  outputs = [ "out" "dev" ];
+
   src = fetchurl {
     url = "mirror://gnome/sources/${pname}/${lib.versions.majorMinor version}/${pname}-${version}.tar.xz";
     sha256 = "0513aad38e5d3cedd4ae3c551634e3be1b9baaa79775e53b2dba9456f15b01c9";
@@ -22,9 +25,10 @@ stdenv.mkDerivation rec {
     gobject-introspection
   ];
 
-  buildInputs = [
+  propagatedBuildInputs = [
     glib
     libsoup
+    libxml2
   ];
 
   configureFlags = [