patch 9.0.0977: it is not easy to see what client-server commands are doing

Problem:    It is not easy to see what client-server commands are doing.
Solution:   Add channel log messages if ch_log() is available.  Move the
            channel logging and make it available with the +eval feature.
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 112a2e7..e72f861 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -1750,9 +1750,9 @@
     {"ch_info",		1, 1, FEARG_1,	    arg1_chan_or_job,
 			ret_dict_any,	    JOB_FUNC(f_ch_info)},
     {"ch_log",		1, 2, FEARG_1,	    arg2_string_chan_or_job,
-			ret_void,	    JOB_FUNC(f_ch_log)},
+			ret_void,	    f_ch_log},
     {"ch_logfile",	1, 2, FEARG_1,	    arg2_string,
-			ret_void,	    JOB_FUNC(f_ch_logfile)},
+			ret_void,	    f_ch_logfile},
     {"ch_open",		1, 2, FEARG_1,	    arg2_string_dict,
 			ret_channel,	    JOB_FUNC(f_ch_open)},
     {"ch_read",		1, 2, FEARG_1,	    arg2_chan_or_job_dict,