libiberty: Add dev output

lib/maintainers.nix

···
   eqyiel = "Ruben Maher <[e-mail]>";
   ericbmerritt = "Eric Merritt <[e-mail]>";
   ericsagnes = "Eric Sagnes <[e-mail]>";
+  ericson2314 = "John Ericson <[e-mail]>";
   erictapen = "Justin Humm <[e-mail]>";
   erikryb = "Erik Rybakken <[e-mail]>";
   ertes = "Ertugrul Söylemez <[e-mail]>";

pkgs/development/libraries/libiberty/default.nix

···
-{ stdenv, lib, fetchurl, gcc, staticBuild ? false }:
+{ stdenv, fetchurl, gcc, staticBuild ? false }:
 
 stdenv.mkDerivation rec {
   name = "libiberty-${gcc.cc.version}";
 
   inherit (gcc.cc) src;
 
+  outputs = [ "out" "dev" ];
+
   postUnpack = "sourceRoot=\${sourceRoot}/libiberty";
 
-  configureFlags = [ "--enable-install-libiberty" ] ++ lib.optional (!staticBuild) "--enable-shared";
+  configureFlags = [ "--enable-install-libiberty" ]
+    ++ stdenv.lib.optional (!staticBuild) "--enable-shared";
 
-  postInstall = lib.optionalString (!staticBuild) ''
+  postInstall = stdenv.lib.optionalString (!staticBuild) ''
     cp pic/libiberty.a $out/lib*/libiberty.a
   '';
 
···
     homepage = http://gcc.gnu.org/;
     license = licenses.lgpl2;
     description = "Collection of subroutines used by various GNU programs";
-    maintainers = with maintainers; [ abbradar ];
+    maintainers = with maintainers; [ abbradar ericson2314 ];
     platforms = platforms.unix;
   };
 }