msvc: Adjust the object directory

* Update a comment. It's not one of eight directories. It's now 1/3072.
* Don't add 'X' infix for CUI even when `DIRECTX=yes`. No need to use a
  different directory.
* Use different object directory for `USE_MSVCRT`.

src/Make_mvc.mak

@@ -192,8 +192,7 @@ GUI = yes
 DIRECTX = $(GUI)
 !endif
 
-# Select one of eight object code directories, depends on GUI, OLE, DEBUG and
-# interfaces.
+# Select a code directory, depends on GUI, OLE, DEBUG, interfaces and etc.
 # If you change something else, do "make clean" first!
 !if "$(VIMDLL)" == "yes"
 OBJDIR = .\ObjD
@@ -202,7 +201,7 @@ OBJDIR = .\ObjG
 !else
 OBJDIR = .\ObjC
 !endif
-!if "$(DIRECTX)" == "yes"
+!if "$(DIRECTX)" == "yes" && "$(GUI)" == "yes"
 OBJDIR = $(OBJDIR)X
 !endif
 !if "$(OLE)" == "yes"
@@ -229,6 +228,9 @@ OBJDIR = $(OBJDIR)R
 !ifdef MZSCHEME
 OBJDIR = $(OBJDIR)Z
 !endif
+!ifdef USE_MSVCRT
+OBJDIR = $(OBJDIR)V
+!endif
 !if "$(DEBUG)" == "yes"
 OBJDIR = $(OBJDIR)d
 !endif