patch 8.2.4038: various code not used when features are disabled

Problem:    Various code not used when features are disabled.
Solution:   Add #ifdefs. (Dominique Pellé, closes #9491)
diff --git a/src/evalbuffer.c b/src/evalbuffer.c
index b6bd67b..1b82984 100644
--- a/src/evalbuffer.c
+++ b/src/evalbuffer.c
@@ -864,9 +864,7 @@
 }
 #endif  // FEAT_EVAL
 
-#if defined(FEAT_JOB_CHANNEL) \
-	|| defined(FEAT_PYTHON) || defined(FEAT_PYTHON3) \
-	|| defined(PROTO)
+#if defined(FEAT_PYTHON) || defined(FEAT_PYTHON3) || defined(PROTO)
 /*
  * Make "buf" the current buffer.  restore_buffer() MUST be called to undo.
  * No autocommands will be executed.  Use aucmd_prepbuf() if there are any.