patch 8.1.0735: cannot handle binary data

Problem:    Cannot handle binary data.
Solution:   Add the Blob type. (Yasuhiro Matsumoto, closes #3638)
diff --git a/src/proto.h b/src/proto.h
index cbd4460..af34dc9 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -88,6 +88,7 @@
 # include "hashtab.pro"
 # include "json.pro"
 # include "list.pro"
+# include "blob.pro"
 # include "main.pro"
 # include "mark.pro"
 # include "memfile.pro"