patch 8.1.0880: MS-Windows: inconsistent selection of winpty/conpty

Problem:    MS-Windows: inconsistent selection of winpty/conpty.
Solution:   Name option 'termwintype', use ++type argument and "term_pty" for
            term_start(). (Hirohito Higashi, closes #3915)
diff --git a/src/option.h b/src/option.h
index 2985781..26e5fd0 100644
--- a/src/option.h
+++ b/src/option.h
@@ -834,6 +834,9 @@
 #ifdef FEAT_TERMGUICOLORS
 EXTERN int	p_tgc;		/* 'termguicolors' */
 #endif
+#if defined(WIN3264) && defined(FEAT_TERMINAL)
+EXTERN char_u	*p_twt;		// 'termwintype'
+#endif
 EXTERN int	p_terse;	/* 'terse' */
 EXTERN int	p_ta;		/* 'textauto' */
 EXTERN int	p_to;		/* 'tildeop' */
@@ -1112,7 +1115,6 @@
 #ifdef FEAT_TERMINAL
     , WV_TWK
     , WV_TWS
-    , WV_TMOD
 #endif
     , WV_CRBIND
 #ifdef FEAT_LINEBREAK