Show stagestats for dependent precompilation

This way you can get much more info when your "stage parse"
takes long, and you can more easily see the dependency
structure of your projects (though of course modules that
were already precompiled won't show up here)

src/core/CompUnit/PrecompilationRepository.pm6

@@ -260,6 +260,12 @@ class CompUnit::PrecompilationRepository::Default does CompUnit::PrecompilationR
         my $out = '';
         my $err = '';
         my $status;
+        #note "running PrecompRepo.precompile";
+        #note "is stagestats set? { +%*COMPILING<%?OPTIONS><stagestats> } { ~%*COMPILING<%?OPTIONS><stagestats> }";
+        with %*COMPILING<%?OPTIONS><stagestats> {
+            note "\nprecomp $path.relative()";
+            $*ERR.flush;
+        }
         react {
             my $proc = Proc::Async.new(
                 $perl6,
@@ -269,6 +275,7 @@ class CompUnit::PrecompilationRepository::Default does CompUnit::PrecompilationR
                 "--target=" ~ Rakudo::Internals.PRECOMP-TARGET,
                 "--output=$bc",
                 "--source-name=$source-name",
+                |("--stagestats" with %*COMPILING<%?OPTIONS><stagestats>),
                 $path
             );
 
@@ -280,6 +287,11 @@ class CompUnit::PrecompilationRepository::Default does CompUnit::PrecompilationR
                     $err ~= $_
                 }
             }
+            with %*COMPILING<%?OPTIONS><stagestats> {
+                whenever $proc.stderr.lines {
+                    note("    $_");
+                }
+            }
             whenever $proc.start(ENV => %env) {
                 $status = .exitcode
             }
@@ -293,7 +305,7 @@ class CompUnit::PrecompilationRepository::Default does CompUnit::PrecompilationR
             die $RMD ?? @result !! $err;
         }
 
-        if not $RMD and $err -> $warnings {
+        if not $RMD and not %*COMPILING<%?OPTIONS><stagestats>:exists and $err -> $warnings {
             $*ERR.print($warnings);
         }
         unless $bc.e {