add a little tool for analyzing modules/ for missing stuff

tools/star/analyze_module_dependencies.p6

@@ -0,0 +1,38 @@
+my %depended-on := SetHash.new;
+my @has-names;
+
+use JSON::Fast;
+
+for qx{ ls modules/*/META* }.lines -> $jf {
+
+    my $data = from-json(slurp($jf));
+
+    # list module as available
+    @has-names.push($data<name>);
+
+    # these three can contain dependencies
+    for <depends test-depends build-depends> -> $_ {
+        # but some of them are optional
+        next unless $data{$_}:exists;
+        my $val = $data{$_};
+        # and sometimes they are just an empty array in the json blob.
+        next if $val.elems == 0;
+
+        # record every dependency in our set
+        %depended-on{@$val}>>++;
+    }
+}
+
+# exclude a few modules:
+# Panda doesn't have a META.info
+# Test is shipped with Rakudo
+# NativeCall is also shipped with rakudo
+# nqp isn't really a module.
+my @missing = %depended-on (-) @has-names (-) <Panda Test NativeCall nqp>;
+
+with @missing {
+    say "There are some modules that are depended on, but not in the modules list.";
+    .say for @missing;
+} else {
+    say "the modules seem to be sane.";
+}