patch 8.1.2409: creating the distribution doesn't work as documented

Problem:    Creating the distribution doesn't work as documented.
Solution:   Adjust name of uninstall binary. Create src/auto directory if
            needed.
diff --git a/src/Make_mvc.mak b/src/Make_mvc.mak
index 9a01927..1a74d3b 100644
--- a/src/Make_mvc.mak
+++ b/src/Make_mvc.mak
@@ -1570,6 +1570,7 @@
 	$(CC) $(CFLAGS_OUTDIR) $(LUA_INC) if_lua.c
 
 auto/if_perl.c : if_perl.xs typemap
+	-mkdir auto
 	$(XSUBPP) -prototypes -typemap $(XSUBPP_TYPEMAP) \
 		-typemap typemap if_perl.xs -output $@