fix(3p/nix): propagate dependencies which are needed by people linking in nix

This includes absl, which we install into the output, and boost and the boehm GC,
which are moved to propagated deps.

Change-Id: I8f9f9795ff92e26b2320359064241d7fd59c2d33
Reviewed-on: https://cl.tvl.fyi/c/depot/+/549
Reviewed-by: tazjin <mail@tazj.in>

third_party/nix/default.nix

@@ -36,13 +36,11 @@ in pkgs.llvmPackages.libcxxStdenv.mkDerivation {
  # TODO(tazjin): Some of these might only be required for native inputs
   buildInputs = with pkgs; [
     aws-s3-cpp
-    boost
     brotli
     bzip2
     curl
     editline
     flex
-    largeBoehm
     libseccomp
     libsodium
     openssl
@@ -50,6 +48,11 @@ in pkgs.llvmPackages.libcxxStdenv.mkDerivation {
     xz
   ];
 
+  propagatedBuildInputs = with pkgs; [
+    boost
+    largeBoehm
+  ];
+
   # Install the various symlinks to the Nix binary which users expect
   # to exist.
   postInstall = ''