patch 8.2.4912: using execute() to define a lambda doesn't work

Problem:    Using execute() to define a lambda doesn't work. (Ernie Rael)
Solution:   Put the getline function in evalarg. (closes #10375)
diff --git a/src/eval.c b/src/eval.c
index 41094cd..4906fa6 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -140,7 +140,7 @@
     if (eap != NULL)
     {
 	evalarg->eval_cstack = eap->cstack;
-	if (sourcing_a_script(eap))
+	if (sourcing_a_script(eap) || eap->getline == get_list_line)
 	{
 	    evalarg->eval_getline = eap->getline;
 	    evalarg->eval_cookie = eap->cookie;