patch 8.1.1869: code for the argument list is spread out

Problem:    Code for the argument list is spread out.
Solution:   Put argument list code in arglist.c. (Yegappan Lakshmanan,
            closes #4819)
diff --git a/Filelist b/Filelist
index 9b0634d..f5798b3 100644
--- a/Filelist
+++ b/Filelist
@@ -13,6 +13,7 @@
 		src/README.md \
 		src/alloc.h \
 		src/arabic.c \
+		src/arglist.c \
 		src/ascii.h \
 		src/autocmd.c \
 		src/beval.c \
@@ -165,6 +166,7 @@
 		src/proto.h \
 		src/protodef.h \
 		src/proto/arabic.pro \
+		src/proto/arglist.pro \
 		src/proto/autocmd.pro \
 		src/proto/beval.pro \
 		src/proto/blob.pro \