patch 8.0.0848: using multiple ch_log functions is clumsy

Problem:    Using multiple ch_log functions is clumsy.
Solution:   Use variable arguments. (Ozaki Kiichi, closes #1919)
diff --git a/src/terminal.c b/src/terminal.c
index c24ac9e..2c0879d 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -389,10 +389,10 @@
 
     if (term->tl_vterm == NULL)
     {
-	ch_logn(channel, "NOT writing %d bytes to terminal", (int)len);
+	ch_log(channel, "NOT writing %d bytes to terminal", (int)len);
 	return;
     }
-    ch_logn(channel, "writing %d bytes to terminal", (int)len);
+    ch_log(channel, "writing %d bytes to terminal", (int)len);
     term_write_job_output(term, msg, len);
 
     if (!term->tl_terminal_mode)
@@ -1475,7 +1475,7 @@
 	}
 
 	vterm_set_size(vterm, rows, cols);
-	ch_logn(term->tl_job->jv_channel, "Resizing terminal to %d lines",
+	ch_log(term->tl_job->jv_channel, "Resizing terminal to %d lines",
 									 rows);
 	term_report_winsize(term, rows, cols);
     }