cmake: Get rid of circular dependency

Also, don't install static libraries in jsoncpp.

pkgs/development/libraries/jsoncpp/default.nix

@@ -20,18 +20,14 @@ stdenv.mkDerivation rec {
     export sourceRoot=${src.name}
   '';
 
-  nativeBuildInputs = [
-    # cmake can be built with the system jsoncpp, or its own bundled version.
-    # Obviously we cannot build it against the system jsoncpp that doesn't yet exist, so
-    # we make a bootstrapping build with the bundled version.
-    (cmake.override { jsoncpp = null; })
-    python
-  ];
+  nativeBuildInputs = [ cmake python ];
 
   cmakeFlags = [
     "-DJSONCPP_WITH_CMAKE_PACKAGE=1"
   ];
 
+  postInstall = "rm $out/lib/*.a";
+
   meta = {
     inherit version;
     homepage = https://github.com/open-source-parsers/jsoncpp;

pkgs/development/tools/build-managers/cmake/default.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchurl
-, bzip2, curl, expat, jsoncpp, libarchive, xz, zlib
+, bzip2, curl, expat, libarchive, xz, zlib
 , useNcurses ? false, ncurses, useQt4 ? false, qt4
 , wantPS ? false, ps ? null
 }:
@@ -40,7 +40,6 @@ stdenv.mkDerivation rec {
 
   buildInputs =
     [ bzip2 curl expat libarchive xz zlib ]
-    ++ optional (jsoncpp != null) jsoncpp
     ++ optional useNcurses ncurses
     ++ optional useQt4 qt4;
 
@@ -53,8 +52,8 @@ stdenv.mkDerivation rec {
       "--docdir=/share/doc/${name}"
       "--mandir=/share/man"
       "--system-libs"
+      "--no-system-jsoncpp"
     ]
-    ++ optional (jsoncpp == null) "--no-system-jsoncpp"
     ++ optional useQt4 "--qt-gui";
 
   setupHook = ./setup-hook.sh;