patch 8.1.0825: code for autocommands is mixed with file I/O code

Problem:    Code for autocommands is mixed with file I/O code.
Solution:   Move autocommand code to a separate file. (Yegappan Lakshmanan,
            closes #3863)
diff --git a/src/Make_sas.mak b/src/Make_sas.mak
index a16908e..c621360 100644
--- a/src/Make_sas.mak
+++ b/src/Make_sas.mak
@@ -90,6 +90,7 @@
 
 SRC = \
 	arabic.c \
+	autocmd.c \
 	blowfish.c \
 	buffer.c \
 	charset.c \
@@ -148,6 +149,7 @@
 
 OBJ = \
 	arabic.o \
+	autocmd.o \
 	blowfish.o \
 	buffer.o \
 	charset.o \
@@ -206,6 +208,7 @@
 
 PRO = \
 	proto/arabic.pro \
+	proto/autocmd.pro \
 	proto/blowfish.pro \
 	proto/buffer.pro \
 	proto/charset.pro \
@@ -319,6 +322,8 @@
 # dependencies
 arabic.o:		arabic.c
 proto/arabic.pro:	arabic.c
+autocmd.o:		autocmd.c
+proto/autocmd.pro:	autocmd.c
 blowfish.o:		blowfish.c
 proto/blowfish.pro:	blowfish.c
 buffer.o:		buffer.c