patch 8.2.0861: cannot easily get all the current marks

Problem:    Cannot easily get all the current marks.
Solution:   Add getmarklist(). (Yegappan Lakshmanan, closes #6032)
diff --git a/src/proto/mark.pro b/src/proto/mark.pro
index a28fa9a..cc45f0d 100644
--- a/src/proto/mark.pro
+++ b/src/proto/mark.pro
@@ -27,4 +27,5 @@
 void set_last_cursor(win_T *win);
 void free_all_marks(void);
 xfmark_T *get_namedfm(void);
+void f_getmarklist(typval_T *argvars, typval_T *rettv);
 /* vim: set ft=c : */