[GR-15260] Ensure the C mutex is reclaimed with the standard unblocker.

PullRequest: truffleruby/804

Author: aardvark179

lib/truffle/truffle/cext.rb

@@ -1640,11 +1640,10 @@ def rb_thread_call_without_gvl(function, data1, unblock, data2)
       }
     end
 
-    runner = -> {
-      Truffle.invoke_primitive(:call_without_c_mutex, function, [data1])
-    }
-
-    Thread.current.unblock unblocker, runner
+    Truffle.invoke_primitive( :call_without_c_mutex,
+                              -> { Thread.current.unblock(
+                                     unblocker,
+                                     -> { function.call(data1) }) }, [])
   end
 
   def rb_iterate(iteration, iterated_object, callback, callback_arg)