patch 8.0.0742: terminal feature does not work on MS-Windows

Problem:    Terminal feature does not work on MS-Windows.
Solution:   Use libvterm and libwinpty on MS-Windows. (Yasuhiro Matsumoto)
diff --git a/src/proto/channel.pro b/src/proto/channel.pro
index e576584..0727b8c 100644
--- a/src/proto/channel.pro
+++ b/src/proto/channel.pro
@@ -55,6 +55,8 @@
 void free_job_options(jobopt_T *opt);
 int get_job_options(typval_T *tv, jobopt_T *opt, int supported);
 channel_T *get_channel_arg(typval_T *tv, int check_open, int reading, ch_part_T part);
+job_T *job_alloc(void);
+void job_cleanup(job_T *job);
 void job_free_all(void);
 int set_ref_in_job(int copyID);
 void job_unref(job_T *job);