patch 8.1.2027: MS-Windows: problem with ambiwidth characters

Problem:    MS-Windows: problem with ambiwidth characters.
Solution:   handle ambiguous width characters in ConPTY on Windows 10 (1903).
            (Nobuhiro Takasaki, closes #4411)
diff --git a/src/Make_mvc.mak b/src/Make_mvc.mak
index 5c9553a..7aa7ef8 100644
--- a/src/Make_mvc.mak
+++ b/src/Make_mvc.mak
@@ -1716,6 +1716,7 @@
 	-DVSNPRINTF=vim_vsnprintf \
 	-DIS_COMBINING_FUNCTION=utf_iscomposing_uint \
 	-DWCWIDTH_FUNCTION=utf_uint2cells \
+	-DGET_SPECIAL_PTY_TYPE_FUNCTION=get_special_pty_type \
 	-D_CRT_SECURE_NO_WARNINGS
 
 # Create a default rule for libvterm.