nix-doc: 0.5.9 -> 0.5.10

Fixes https://github.com/NixOS/nixpkgs/issues/237637 and its entire
class of problems by making nix-doc save the version it was built for in
the library and then bail harmlessly if it is mismatched.

```
dev/nixpkgs2 » nix-build -A nix-doc
/nix/store/wv9nm47lplyz4b0pa4549zwrnsp3zvaf-nix-doc-0.5.10
dev/nixpkgs2 » nix-build -A nixVersions.nix_2_14 -o result2
/nix/store/ka0ygdzl9jd0j77y7ls6shngdz9vvqpn-nix-2.14.1
dev/nixpkgs2 » ./result2/bin/nix --plugin-files ./result/lib/libnix_doc_plugin.so repl
nix-doc warning: mismatched nix version, not loading
Welcome to Nix 2.14.1. Type :? for help.

nix-repl>
```

pkgs/tools/package-management/nix-doc/default.nix

···
-{ lib, rustPlatform, fetchFromGitHub, boost, nix, pkg-config }:
+{ lib, stdenv, rustPlatform, fetchFromGitHub, boost, nix, pkg-config }:
 
 rustPlatform.buildRustPackage rec {
   pname = "nix-doc";
-  version = "0.5.9";
+  version = "0.5.10";
 
   src = fetchFromGitHub {
     rev = "v${version}";
     owner = "lf-";
     repo = "nix-doc";
-    sha256 = "sha256-uilVJz1MnMF3i/ZXY0bIoSK3uAzfxWuHfhoOSmQgY/I=";
+    sha256 = "sha256-+T4Bz26roTFiXTM8P8FnJLSdFY2hP26X4nChWWUACN8=";
   };
 
   doCheck = true;
···
 
   nativeBuildInputs = [ pkg-config nix ];
 
-  cargoSha256 = "sha256-02noJcbtml4MxRCjaWtjOWLTUNOQnKy3GCsil31J6F8=";
+  # Packaging support for making the nix-doc plugin load cleanly as a no-op on
+  # the wrong Nix version (disabling bindnow permits loading libraries
+  # requiring unavailable symbols if they are unreached)
+  hardeningDisable = [ "bindnow" ];
+  # Due to a Rust bug, setting -Z relro-level to anything including "off" on
+  # macOS will cause link errors
+  env = lib.optionalAttrs stdenv.isLinux {
+    # nix-doc does not use nightly features, however, there is no other way to
+    # set relro-level
+    RUSTC_BOOTSTRAP = 1;
+    RUSTFLAGS = "-Z relro-level=partial";
+  };
+
+  cargoSha256 = "sha256-GylSWo4LIsjKnJE9H6iJHZ99UI6UPhAOnAGXk+v8bko=";
 
   meta = with lib; {
     description = "An interactive Nix documentation tool";