patch 8.0.0751: OpenPTY missing with some combination of features

Problem:    OpenPTY missing with some combination of features. (Kazunobu
            Kuriyama)
Solution:   Adjust #ifdef.  Also include pty.pro when needed.
diff --git a/src/pty.c b/src/pty.c
index a738ac1..9b03612 100644
--- a/src/pty.c
+++ b/src/pty.c
@@ -43,7 +43,7 @@
 
 #include "vim.h"
 
-#if defined(FEAT_GUI) || defined(FEAT_TERMINAL)
+#if defined(FEAT_GUI) || defined(FEAT_JOB_CHANNEL)
 
 #include <signal.h>