release: don't build libseccomp if we're on darwin

release.nix

@@ -27,8 +27,8 @@ let
           [ curl bison flex perl libxml2 libxslt bzip2 xz
             dblatex (dblatex.tex or tetex) nukeReferences pkgconfig sqlite libsodium
             docbook5 docbook5_xsl
-            libseccomp
-          ] ++ lib.optional (!lib.inNixShell) git;
+          ] ++ lib.optional stdenv.isLinux libseccomp
+          ++ lib.optional (!lib.inNixShell) git;
 
         configureFlags = ''
           --with-dbi=${perlPackages.DBI}/${perl.libPrefix}