gbenchmark: add prometheus-cpp as reverse dependency to passthru.tests

pkgs/development/libraries/gbenchmark/default.nix

@@ -1,4 +1,10 @@
-{ lib, stdenv, fetchFromGitHub, cmake, gtest }:
+{ lib
+, stdenv
+, fetchFromGitHub
+, cmake
+, gtest
+, prometheus-cpp
+}:
 
 stdenv.mkDerivation rec {
   pname = "gbenchmark";
@@ -25,6 +31,10 @@ stdenv.mkDerivation rec {
 
   doCheck = true;
 
+  passthru.tests = {
+    inherit prometheus-cpp;
+  };
+
   meta = with lib; {
     description = "A microbenchmark support library";
     homepage = "https://github.com/google/benchmark";