Fix PBuiltinFunction#toString not to use context

Author: msimacek

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/function/PBuiltinFunction.java

@@ -130,11 +130,7 @@ public Object getEnclosingType() {
     @Override
     public String toString() {
         CompilerAsserts.neverPartOfCompilation();
-        if (enclosingType == null) {
-            return String.format("PBuiltinFunction %s at 0x%x", name, hashCode());
-        } else {
-            return String.format("PBuiltinFunction %s.%s at 0x%x", GetNameNode.doSlowPath(enclosingType), name, hashCode());
-        }
+        return String.format("PBuiltinFunction %s at 0x%x", qualname, hashCode());
     }
 
     public PBuiltinFunction boundToObject(PythonBuiltinClassType klass, PythonObjectFactory factory) {