patch 8.1.1876: proto file missing from distribution

Problem:    proto file missing from distribution
Solution:   Add the file.
diff --git a/Filelist b/Filelist
index f5798b3..464d730 100644
--- a/Filelist
+++ b/Filelist
@@ -175,6 +175,7 @@
 		src/proto/change.pro \
 		src/proto/channel.pro \
 		src/proto/charset.pro \
+		src/proto/cmdhist.pro \
 		src/proto/crypt.pro \
 		src/proto/crypt_zip.pro \
 		src/proto/debugger.pro \