patch 8.1.1512: ch_evalexpr() hangs when used recursively

Problem:    ch_evalexpr() hangs when used recursively. (Paul Jolly)
Solution:   Change ch_block_id from a single number to a list of IDs to wait
            on.
diff --git a/src/version.c b/src/version.c
index 97dc393..3b434a3 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1512,
+/**/
     1511,
 /**/
     1510,