Stop nqp::can(EXPORTHOW, 'foo') from exploding by adding some missing…

… bits to NQPModuleHOW.

src/how/NQPModuleHOW.pm

@@ -39,8 +39,14 @@ knowhow NQPModuleHOW {
     }
 
     method compose($obj) {
+        pir::publish_method_cache($obj, my %empty);
+        pir::set_method_cache_authoritativeness__0Pi($obj, 1);
         $!composed := 1;
     }
+
+    method find_method($obj, $name, *%opts) {
+        nqp::null()
+    }
 
     method name($obj) {
         $!name