Inline buildDone from DerivationGoal into use sites

The basic idea is that while we have duplicated this function, we now
have one call-site in the local build case, and one call site in the
build hook case. This unlocks big opportunities to specialize each copy,
since they really shouldn't be doing the same things. By the time we are
are done, there should not be much duplication left.

See #12628 for further info.

src/libstore/build/derivation-goal.cc

@@ -640,7 +640,7 @@ Goal::Co DerivationGoal::tryToBuild()
                 buildResult.startTime = time(0); // inexact
                 started();
                 co_await Suspend{};
-                co_return buildDone();
+                co_return hookDone();
             case rpPostpone:
                 /* Not now; wait until at least one child finishes or
                    the wake-up timeout expires. */
@@ -935,7 +935,7 @@ void appendLogTailErrorMsg(
 }
 
 
-Goal::Co DerivationGoal::buildDone()
+Goal::Co DerivationGoal::hookDone()
 {
     trace("build done");
 

src/libstore/build/derivation-goal.hh

@@ -55,6 +55,13 @@ struct InitialOutput {
     std::optional<InitialOutputStatus> known;
 };
 
+/** Used internally */
+void runPostBuildHook(
+    Store & store,
+    Logger & logger,
+    const StorePath & drvPath,
+    const StorePathSet & outputPaths);
+
 /** Used internally */
 void appendLogTailErrorMsg(
     Worker & worker,
@@ -246,7 +253,7 @@ struct DerivationGoal : public Goal
     Co gaveUpOnSubstitution();
     Co tryToBuild();
     virtual Co tryLocalBuild();
-    Co buildDone();
+    Co hookDone();
 
     Co resolvedFinished();