Fix #7655

We had some local variables left over from the older (more
complicated) implementation of this function. They should all be unused,
but one wasn't by mistake.

Delete them all, and replace the one that was still in use as intended.

src/libexpr/primops/context.cc

@@ -83,15 +83,13 @@ static void prim_getContext(EvalState & state, const PosIdx pos, Value * * args,
     state.forceString(*args[0], context, pos, "while evaluating the argument passed to builtins.getContext");
     auto contextInfos = std::map<StorePath, ContextInfo>();
     for (const auto & p : context) {
-        Path drv;
-        std::string output;
         NixStringContextElem ctx = NixStringContextElem::parse(*state.store, p);
         std::visit(overloaded {
             [&](NixStringContextElem::DrvDeep & d) {
                 contextInfos[d.drvPath].allOutputs = true;
             },
             [&](NixStringContextElem::Built & b) {
-                contextInfos[b.drvPath].outputs.emplace_back(std::move(output));
+                contextInfos[b.drvPath].outputs.emplace_back(std::move(b.output));
             },
             [&](NixStringContextElem::Opaque & o) {
                 contextInfos[o.path].path = true;