patch 8.2.4869: expression in command block does not look after NL

Problem:    Expression in command block does not look after NL.
Solution:   Skip over NL to check what follows. (closes #10358)
diff --git a/src/proto/eval.pro b/src/proto/eval.pro
index 49dc65b..e6cd892 100644
--- a/src/proto/eval.pro
+++ b/src/proto/eval.pro
@@ -32,7 +32,7 @@
 void set_context_for_expression(expand_T *xp, char_u *arg, cmdidx_T cmdidx);
 int pattern_match(char_u *pat, char_u *text, int ic);
 char_u *eval_next_non_blank(char_u *arg, evalarg_T *evalarg, int *getnext);
-char_u *eval_next_line(evalarg_T *evalarg);
+char_u *eval_next_line(char_u *arg, evalarg_T *evalarg);
 char_u *skipwhite_and_linebreak(char_u *arg, evalarg_T *evalarg);
 void init_evalarg(evalarg_T *evalarg);
 void clear_evalarg(evalarg_T *evalarg, exarg_T *eap);