patch 9.0.1031: Vim9 class is not implemented yet

Problem:    Vim9 class is not implemented yet.
Solution:   Add very basic class support.
diff --git a/src/viminfo.c b/src/viminfo.c
index 58494d4..2e89fb5 100644
--- a/src/viminfo.c
+++ b/src/viminfo.c
@@ -1370,6 +1370,8 @@
 		    case VAR_JOB:
 		    case VAR_CHANNEL:
 		    case VAR_INSTR:
+		    case VAR_CLASS:
+		    case VAR_OBJECT:
 				     continue;
 		}
 		fprintf(fp, "!%s\t%s\t", this_var->di_key, s);