patch 8.0.0971: 'winptydll' missing from :options

Problem:    'winptydll' missing from :options.
Solution:   Add the entry.
diff --git a/runtime/optwin.vim b/runtime/optwin.vim
index 52f987e..c775363 100644
--- a/runtime/optwin.vim
+++ b/runtime/optwin.vim
@@ -1,7 +1,7 @@
 " These commands create the option window.
 "
 " Maintainer:	Bram Moolenaar <Bram@vim.org>
-" Last Change:	2017 Aug 11
+" Last Change:	2017 Aug 19
 
 " If there already is an option window, jump to that one.
 let buf = bufnr('option-window')
@@ -510,6 +510,10 @@
   call append("$", "termkey\tkey that precedes Vim commands in a terminal window")
   call append("$", "\t(local to window)")
   call <SID>OptionL("tk")
+  if exists("&winptydll")
+    call append("$", "winptydll\tname of the winpty dynamic library")
+    call <SID>OptionG("winptydll", &winptydll)
+  endif
 endif
 
 
diff --git a/src/version.c b/src/version.c
index d820595..9f9b8ab 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    971,
+/**/
     970,
 /**/
     969,