b/t/toolchain-bundle: patch bison to use env for path resolving

Change-Id: I266b30d442aa62f32ffbb6ccbe869012a91bcf0a
Reviewed-on: https://review.monogon.dev/c/monogon/+/4420
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/third_party/nix/default.nix b/third_party/nix/default.nix
index d868e74..eab83d7 100644
--- a/third_party/nix/default.nix
+++ b/third_party/nix/default.nix
@@ -10,6 +10,7 @@
           bazel-unwrapped = import ./pkgs/bazel { pkgs = super; };
           perl = import ./pkgs/perl { pkgs = super; };
           python3Minimal = import ./pkgs/python3 { pkgs = super; };
+          bison = import ./pkgs/bison { pkgs = super; };
         })
         (self: super: {
           vde2 = super.vde2.overrideAttrs (oldAttrs: {