vim-patch:7.4.887

Problem:    Using uninitialized memory for regexp with back reference.
            (Dominique Pelle)
Solution:   Initialize end_lnum.

c2b717ebd6

---

see: "[bug] use of uninitialized memory in regexp_nfa.c with invalid back reference"
     https://groups.google.com/d/msg/vim_dev/JWmrT5-NnPQ/U_TgaRW8AwAJ

src/nvim/regexp_nfa.c

@@ -4048,6 +4048,7 @@ skip_add:
         sub->list.multi[subidx].start_col =
           (colnr_T)(reginput - regline + off);
       }
+      sub->list.multi[subidx].end_lnum = -1;
     } else {
       if (subidx < sub->in_use) {
         save_ptr = sub->list.line[subidx].start;