hydra: Clarify the dependency on BDW-GC.

configure.ac

@@ -42,6 +42,8 @@ AC_CHECK_LIB([expr], [_ZN3nix17parseExprFromFileERNS_9EvalStateESs], [:],
 CPPFLAGS="$old_CPPFLAGS"
 LIBS="$old_LIBS"
 
+PKG_CHECK_MODULES([BDW_GC], [bdw-gc])
+
 AC_CONFIG_FILES([
   Makefile
 

release.nix

@@ -15,7 +15,8 @@ rec {
       inherit officialRelease;
       version = builtins.readFile ./version;
 
-      buildInputs = [ perl libxslt dblatex tetex nukeReferences ] ;
+      buildInputs =
+        [ perl libxslt dblatex tetex nukeReferences pkgconfig boehmgc ] ;
 
       preConfigure = ''
         # TeX needs a writable font cache.
@@ -46,7 +47,7 @@ rec {
       configureFlags = "--with-nix=${nix}";
 
       buildInputs =
-        [ perl makeWrapper libtool nix unzip nukeReferences boehmgc ]
+        [ perl makeWrapper libtool nix unzip nukeReferences pkgconfig boehmgc ]
         ++ (import ./deps.nix) { inherit pkgs; };
 
       hydraPath = stdenv.lib.concatStringsSep ":" (map (p: "${p}/bin") ( [

src/c/Makefile.am

@@ -1,6 +1,8 @@
 bin_PROGRAMS = hydra_eval_jobs
 
 hydra_eval_jobs_SOURCES = hydra_eval_jobs.cc
-hydra_eval_jobs_LDADD = -lmain -lexpr -L$(nix)/lib/nix
-AM_CXXFLAGS = \
- -I$(nix)/include/nix
+hydra_eval_jobs_LDADD = -lmain -lexpr -L$(nix)/lib/nix $(BDW_GC_LIBS)
+
+AM_CXXFLAGS =					\
+ -I$(nix)/include/nix				\
+  $(BDW_GC_CFLAGS)

src/c/hydra_eval_jobs.cc

@@ -1,6 +1,8 @@
 #include <map>
 #include <iostream>
 
+#include <gc/gc_allocator.h>
+
 #include "shared.hh"
 #include "store-api.hh"
 #include "eval.hh"