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/ex_getln.c b/src/ex_getln.c
index 702b63d..60a8a0c 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -2705,12 +2705,12 @@
     int		c,		// normally ':', NUL for ":append"
     void	*cookie UNUSED,
     int		indent,		// indent for inside conditionals
-    int		do_concat)
+    getline_opt_T options)
 {
     // When executing a register, remove ':' that's in front of each line.
     if (exec_from_reg && vpeekc() == ':')
 	(void)vgetc();
-    return getcmdline(c, 1L, indent, do_concat);
+    return getcmdline(c, 1L, indent, options);
 }
 
 /*
@@ -2725,7 +2725,7 @@
 				// :s prompt
     void	*cookie UNUSED,
     int		indent,		// indent for inside conditionals
-    int		do_concat UNUSED)
+    getline_opt_T options UNUSED)
 {
     garray_T	line_ga;
     char_u	*pend;