Implement backwards-compatible RemoteStore::addToStore()

The SSHStore PR adds this functionality to the daemon, but we have to
handle the case where the Nix daemon is 1.11.

Also, don't require signatures for trusted users. This restores 1.11
behaviour.

Fixes https://github.com/NixOS/hydra/issues/398.

release.nix

@@ -25,7 +25,7 @@ let
 
         buildInputs =
           [ curl bison flex perl libxml2 libxslt bzip2 xz
-            pkgconfig sqlite libsodium
+            pkgconfig sqlite libsodium boehmgc
             docbook5 docbook5_xsl
             autoconf-archive
           ] ++ lib.optional (!lib.inNixShell) git;
@@ -34,6 +34,7 @@ let
           --with-dbi=${perlPackages.DBI}/${perl.libPrefix}
           --with-dbd-sqlite=${perlPackages.DBDSQLite}/${perl.libPrefix}
           --with-www-curl=${perlPackages.WWWCurl}/${perl.libPrefix}
+          --enable-gc
         '';
 
         postUnpack = ''