8064375: Change certain errors to warnings in CDS output.

Summary: Change CDS non-fatal preloading errors to warnings.
Reviewed-by: minqi, mseledtsov, coleenp

src/share/vm/classfile/classLoader.cpp

@@ -1137,7 +1137,7 @@ instanceKlassHandle ClassLoader::load_classfile(Symbol* h_name, TRAPS) {
     h = context.record_result(classpath_index, e, result, THREAD);
   } else {
     if (DumpSharedSpaces) {
-      tty->print_cr("Preload Error: Cannot find %s", class_name);
+      tty->print_cr("Preload Warning: Cannot find %s", class_name);
     }
   }
 

src/share/vm/classfile/dictionary.cpp

@@ -223,7 +223,7 @@ void Dictionary::remove_classes_in_error_state() {
         }
         free_entry(probe);
         ResourceMark rm;
-        tty->print_cr("Removed error class: %s", ik->external_name());
+        tty->print_cr("Preload Warning: Removed error class: %s", ik->external_name());
         continue;
       }
 

src/share/vm/memory/metaspaceShared.cpp

@@ -851,7 +851,7 @@ bool MetaspaceShared::try_link_class(InstanceKlass* ik, TRAPS) {
     ik->link_class(THREAD);
     if (HAS_PENDING_EXCEPTION) {
       ResourceMark rm;
-      tty->print_cr("Preload Error: Verification failed for %s",
+      tty->print_cr("Preload Warning: Verification failed for %s",
                     ik->external_name());
       CLEAR_PENDING_EXCEPTION;
       ik->set_in_error_state();