patch 8.2.1074: Vim9: no line break allowed after some operators

Problem:    Vim9: no line break allowed after some operators.
Solution:   Skip a line break after the operator.  Add
            eval_may_get_next_line() to simplify checking for a line break.
diff --git a/src/proto/eval.pro b/src/proto/eval.pro
index c66e331..9170385 100644
--- a/src/proto/eval.pro
+++ b/src/proto/eval.pro
@@ -29,6 +29,7 @@
 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 *skipwhite_and_linebreak(char_u *arg, evalarg_T *evalarg);
 int eval0(char_u *arg, typval_T *rettv, exarg_T *eap, evalarg_T *evalarg);
 int eval1(char_u **arg, typval_T *rettv, evalarg_T *evalarg);
 void eval_addblob(typval_T *tv1, typval_T *tv2);