8209138: Symbol constructor uses u1 as the element type of its name argument

Maske u1 the type for Symbol values and add a function to return it as a char.

Reviewed-by: dholmes, coleenp

src/hotspot/share/ci/ciObjectFactory.cpp

@@ -466,7 +466,7 @@ ciKlass* ciObjectFactory::get_unloaded_klass(ciKlass* accessing_klass,
 
   // Two cases: this is an unloaded ObjArrayKlass or an
   // unloaded InstanceKlass.  Deal with both.
-  if (name->byte_at(0) == '[') {
+  if (name->char_at(0) == '[') {
     // Decompose the name.'
     FieldArrayInfo fd;
     BasicType element_type = FieldType::get_array_info(name->get_symbol(),