patch 8.1.1978: the eval.c file is too big

Problem:    The eval.c file is too big.
Solution:   Move filter() and map() to list.c.
diff --git a/src/version.c b/src/version.c
index 9481a3d..3e06f92 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1978,
+/**/
     1977,
 /**/
     1976,