Revert back to only cleaning targets in subdirectories

Cleaning everything as long as it is in the same strong amalgamation had
some undesirable side effects. For example, in bpkg, upgrading a package
(which requires clean/reconfigure) led to all its prerequisite being
cleaned as well and then rebuilt. That was very surprising.

1 files changed, 2 insertions, 7 deletions

diff --git a/build2/cxx/compile.cxx b/build2/cxx/compile.cxx
index a1abfcb..22a25cb 100644
--- a/build2/cxx/compile.cxx
+++ b/build2/cxx/compile.cxx
@@ -78,13 +78,8 @@ namespace build2
       // code (below) takes care of the ones it is adding.
       //
       // When cleaning, ignore prerequisites that are not in the same
-      // or a subdirectory of our strong amalgamation.
+      // or a subdirectory of ours.
       //
-      const dir_path* amlg (
-        a.operation () != clean_id
-        ? nullptr
-        : &t.strong_scope ().out_path ());
-
       link::search_paths_cache lib_paths; // Extract lazily.
 
       for (prerequisite_member p: group_prerequisite_members (a, t))
@@ -117,7 +112,7 @@ namespace build2
 
         target& pt (p.search ());
 
-        if (a.operation () == clean_id && !pt.dir.sub (*amlg))
+        if (a.operation () == clean_id && !pt.dir.sub (t.dir))
           continue;
 
         build2::match (a, pt);