Merge branch 'staging-next'

It's not completely without regressions, but ATM it seems to bring more
upsides than downsides and the iteration is too long already.

pkgs/development/tools/misc/hydra/default.nix

@@ -87,7 +87,7 @@ in releaseTools.nixBuild rec {
   };
 
   buildInputs =
-    [ makeWrapper autoconf automake libtool unzip nukeReferences pkgconfig sqlite libpqxx
+    [ makeWrapper autoconf automake libtool unzip nukeReferences sqlite libpqxx
       gitAndTools.topGit mercurial darcs subversion bazaar openssl bzip2 libxslt
       guile # optional, for Guile + Guix support
       perlDeps perl nix
@@ -100,7 +100,7 @@ in releaseTools.nixBuild rec {
       gzip bzip2 lzma gnutar unzip git gitAndTools.topGit mercurial darcs gnused bazaar
     ] ++ lib.optionals stdenv.isLinux [ rpm dpkg cdrkit ] );
 
-  nativeBuildInputs = [ autoreconfHook ];
+  nativeBuildInputs = [ autoreconfHook pkgconfig ];
 
   # adds a patch which ensures compatibility with the API of Nix 2.0.
   # it has been reverted in https://github.com/NixOS/hydra/commit/162d671c48a418bd10a8a171ca36787ef3695a44,
@@ -114,6 +114,8 @@ in releaseTools.nixBuild rec {
 
   configureFlags = [ "--with-docbook-xsl=${docbook_xsl}/xml/xsl/docbook" ];
 
+  NIX_CFLAGS_COMPILE = [ "-pthread" ];
+
   shellHook = ''
     PATH=$(pwd)/src/script:$(pwd)/src/hydra-eval-jobs:$(pwd)/src/hydra-queue-runner:$(pwd)/src/hydra-evaluator:$PATH
     PERL5LIB=$(pwd)/src/lib:$PERL5LIB;