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_cyg_ming.mak b/src/Make_cyg_ming.mak
index 7aef61a..8d8666f 100644
--- a/src/Make_cyg_ming.mak
+++ b/src/Make_cyg_ming.mak
@@ -695,6 +695,7 @@
 CUIOBJ = $(OUTDIR)/iscygpty.o
 OBJ = \
 	$(OUTDIR)/arabic.o \
+	$(OUTDIR)/autocmd.o \
 	$(OUTDIR)/beval.o \
 	$(OUTDIR)/blob.o \
 	$(OUTDIR)/blowfish.o \