Give Derivation::tryResolve an evalStore argument

*N.B. Backport is modified not to change any call sites / behavior.*

This is needed for building CA deriations with a src store / dest store
split. In particular it is needed for Hydra.

NixOS/hydra#838 currently puts realizations,
and thus build outputs, in the local store, but it should not.

(cherry picked with modifications from commit 96dd757)

src/libstore/derivations.cc

@@ -1002,13 +1002,13 @@ static void rewriteDerivation(Store & store, BasicDerivation & drv, const String
 
 }
 
-std::optional<BasicDerivation> Derivation::tryResolve(Store & store) const
+std::optional<BasicDerivation> Derivation::tryResolve(Store & store, Store * evalStore) const
 {
     std::map<std::pair<StorePath, std::string>, StorePath> inputDrvOutputs;
 
     std::function<void(const StorePath &, const DerivedPathMap<StringSet>::ChildNode &)> accum;
     accum = [&](auto & inputDrv, auto & node) {
-        for (auto & [outputName, outputPath] : store.queryPartialDerivationOutputMap(inputDrv)) {
+        for (auto & [outputName, outputPath] : store.queryPartialDerivationOutputMap(inputDrv, evalStore)) {
             if (outputPath) {
                 inputDrvOutputs.insert_or_assign({inputDrv, outputName}, *outputPath);
                 if (auto p = get(node.childMap, outputName))

src/libstore/derivations.hh

@@ -340,7 +340,7 @@ struct Derivation : BasicDerivation
      * 2. Input placeholders are replaced with realized input store
      *    paths.
      */
-    std::optional<BasicDerivation> tryResolve(Store & store) const;
+    std::optional<BasicDerivation> tryResolve(Store & store, Store * evalStore = nullptr) const;
 
     /**
      * Like the above, but instead of querying the Nix database for