patch 8.0.1178: using old compiler on MS-Windows

Problem:    Using old compiler on MS-Windows.
Solution:   Switch default build on MS-Windows to use MSVC 2015. (Ken Takata)
diff --git a/src/tee/Make_mvc.mak b/src/tee/Make_mvc.mak
index 7fe22df..950100d 100644
--- a/src/tee/Make_mvc.mak
+++ b/src/tee/Make_mvc.mak
@@ -1,10 +1,15 @@
 # A very (if not the most) simplistic Makefile for MSVC
 
+SUBSYSTEM = console
+!if "$(SUBSYSTEM_VER)" != ""
+SUBSYSTEM = $(SUBSYSTEM),$(SUBSYSTEM_VER)
+!endif
+
 CC=cl
 CFLAGS=/O2 /nologo
 
 tee.exe: tee.obj
-	$(CC) $(CFLAGS) /Fo$@ $**
+	$(CC) $(CFLAGS) /Fo$@ $** /link /subsystem:$(SUBSYSTEM)
 
 tee.obj: tee.c
 	$(CC) $(CFLAGS) /c $**