patch 8.2.1597: the channel source file is too big

Problem:    The channel source file is too big.
Solution:   Move job related code to a new source file.
diff --git a/src/auto/configure b/src/auto/configure
index e66162f..37a60fa 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -8006,9 +8006,9 @@
 if test "$enable_channel" = "yes"; then
   $as_echo "#define FEAT_JOB_CHANNEL 1" >>confdefs.h
 
-  CHANNEL_SRC="channel.c"
+  CHANNEL_SRC="job.c channel.c"
 
-  CHANNEL_OBJ="objects/channel.o"
+  CHANNEL_OBJ="objects/job.o objects/channel.o"
 
 fi