patch 8.2.1491: Vim9: crash when compiling heredoc lines start with comment

Problem:    Vim9: crash when compiling heredoc lines start with comment.
Solution:   Skip over NULL pointers. Do not remove comment and empty lines
            when fetching function lines. (closes #6743)
diff --git a/src/proto/ex_getln.pro b/src/proto/ex_getln.pro
index f64bb1f..faecab2 100644
--- a/src/proto/ex_getln.pro
+++ b/src/proto/ex_getln.pro
@@ -9,8 +9,8 @@
 int text_locked(void);
 int curbuf_locked(void);
 int allbuf_locked(void);
-char_u *getexline(int c, void *cookie, int indent, int do_concat);
-char_u *getexmodeline(int promptc, void *cookie, int indent, int do_concat);
+char_u *getexline(int c, void *cookie, int indent, getline_opt_T options);
+char_u *getexmodeline(int promptc, void *cookie, int indent, getline_opt_T options);
 int cmdline_overstrike(void);
 int cmdline_at_end(void);
 colnr_T cmdline_getvcol_cursor(void);