patch 8.1.2107: various memory leaks reported by asan
Problem: Various memory leaks reported by asan.
Solution: Free the memory. (Ozaki Kiichi, closes #5003)
diff --git a/src/proto/change.pro b/src/proto/change.pro
index f6b3599..c31c442 100644
--- a/src/proto/change.pro
+++ b/src/proto/change.pro
@@ -7,6 +7,7 @@
void f_listener_remove(typval_T *argvars, typval_T *rettv);
void may_invoke_listeners(buf_T *buf, linenr_T lnum, linenr_T lnume, int added);
void invoke_listeners(buf_T *buf);
+void remove_listeners(buf_T *buf);
void changed_bytes(linenr_T lnum, colnr_T col);
void appended_lines(linenr_T lnum, long count);
void appended_lines_mark(linenr_T lnum, long count);