patch 8.0.0756: cannot build libvterm with MSVC

Problem:    Cannot build libvterm with MSVC.
Solution:   Add an MSVC Makefile to libvterm. (Yasuhiro Matsumoto, closes
            #1865)

src/INSTALLpc.txt

@@ -706,17 +706,20 @@ Or when using MinGW (as one line):
 13. Building with Terminal support
 ==================================
 
-Vim with Terminal support can be built with MinGW or Cygwin.
-Terminal support require winpty which provide following two files.
+Vim with Terminal support can be built with either MSVC, or MinGW or Cygwin.
+This uses the included libvterm and winpty.  No extra header files or
+libraries are needed for building.
+
+Running Vim with terminal support requires the following two winpty files:
 
     winpty.dll
     winpty-agent.dll
 
-You can download following page:
+You can download them from the following page:
 
     https://github.com/rprichard/winpty
 
-It don't need header files or libraries. Just put them on your PATH.
+Just put the DLL files somewhere in your PATH.
 
 
 14. Windows 3.1x

src/Make_mvc.mak

@@ -36,6 +36,8 @@
 #	  is yes)
 #	Global IME support: GIME=yes (requires GUI=yes)
 #
+#       Terminal support: TERMINAL=yes (default is no)
+#
 #	Lua interface:
 #	  LUA=[Path to Lua directory]
 #	  DYNAMIC_LUA=yes (to load the Lua DLL dynamically)
@@ -354,7 +356,8 @@ CSCOPE_DEFS  = -DFEAT_CSCOPE
 !if "$(TERMINAL)" == "yes"
 TERMINAL_OBJ   = $(OBJDIR)/terminal.obj
 TERMINAL_DEFS  = -DFEAT_TERMINAL
-TERMINAL_SRC	= terminal.c
+TERMINAL_SRC   = terminal.c
+VTERM_LIB      = libvterm/vterm.lib
 !endif
 
 !ifndef NETBEANS
@@ -1130,7 +1133,7 @@ conflags = $(conflags) /map /mapinfo:lines
 LINKARGS1 = $(linkdebug) $(conflags)
 LINKARGS2 = $(CON_LIB) $(GUI_LIB) $(NODEFAULTLIB) $(LIBC) $(OLE_LIB) user32.lib \
 		$(LUA_LIB) $(MZSCHEME_LIB) $(PERL_LIB) $(PYTHON_LIB) $(PYTHON3_LIB) $(RUBY_LIB) \
-		$(TCL_LIB) $(NETBEANS_LIB) $(XPM_LIB) $(LINK_PDB)
+		$(TCL_LIB) $(NETBEANS_LIB) $(VTERM_LIB) $(XPM_LIB) $(LINK_PDB)
 
 # Report link time code generation progress if used. 
 !ifdef NODEBUG
@@ -1544,5 +1547,9 @@ proto.h: \
 .c.i:
 	$(CC) $(CFLAGS) /P /C $<
 
+libvterm/vterm.lib :
+	cd libvterm
+	$(MAKE) /NOLOGO -f Makefile.msc
+	cd ..
 
 # vim: set noet sw=8 ts=8 sts=0 wm=0 tw=0:

src/libvterm/Makefile.msc

@@ -0,0 +1,30 @@
+OBJS = \
+	src\encoding.c \
+	src\keyboard.c \
+	src\mouse.c \
+	src\parser.c \
+	src\pen.c \
+	src\screen.c \
+	src\state.c \
+	src\unicode.c \
+	src\vterm.c
+
+OBJS = \
+	src\encoding.obj \
+	src\keyboard.obj \
+	src\mouse.obj \
+	src\parser.obj \
+	src\pen.obj \
+	src\screen.obj \
+	src\state.obj \
+	src\unicode.obj \
+	src\vterm.obj
+
+all : vterm.lib
+
+
+.c.obj :
+	cl /DINLINE= /Iinclude /Fo$@ /c $<
+
+vterm.lib : $(OBJS)
+	lib /OUT:$@ $(OBJS)

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    756,
 /**/
     755,
 /**/