gtest: Fix for or-conf

Assisted-by: Claude Code (Claude Sonnet 5)
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015nagR3thVVbRLcqE9rSr6w

pkgs/by-name/gt/gtest/package.nix

@@ -50,8 +50,9 @@ stdenv.mkDerivation (finalAttrs: {
   nativeBuildInputs = [
     cmake
     ninja
-  ]
-  ++ lib.optionals withAbseil [
+  ];
+
+  buildInputs = lib.optionals withAbseil [
     abseil-cpp
     re2
   ];