patch 8.0.0693: no terminal emulator support

Problem:    No terminal emulator support.  Cannot properly run commands in the
            GUI.  Cannot run a job interactively with an ssh connection.
Solution:   Very early implementation of the :terminal command.  Includes
            libvterm converted to ANSI C.  Many parts still missing.
diff --git a/src/proto.h b/src/proto.h
index 8cfdb12..729fea3 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -162,6 +162,9 @@
 # include "syntax.pro"
 # include "tag.pro"
 # include "term.pro"
+# ifdef FEAT_TERMINAL
+#  include "terminal.pro"
+# endif
 # if defined(HAVE_TGETENT) && (defined(AMIGA) || defined(VMS))
 #  include "termlib.pro"
 # endif