tui.c: Do not wait for tui loop on teardown. (#4789)

Because terminfo_stop() already ran, there is not much reason to wait
for the loop to teardown.

Helped-by: Björn Linse <bjorn.linse@gmail.com>
Helped-by: oni-link <knil.ino@gmail.com>

Closes #4778
References #3541
---
Bug report:

> After pressing `ZZ` I can find two threads freezing, occupying 100% CPU:
    |-systemd-+
              |-nvim,11567 /home/lz/code/1.rs +set title
              |   `-{nvim},11574

> 11567 has two threads:
    (gdb) info threads
      Id   Target Id         Frame
    * 1    Thread 0x7f7622907780 (LWP 11567) "nvim" 0x00007f76222e66bd in pthread_join () from /usr/lib/libpthread.so.0
      2    Thread 0x7f761f5ff700 (LWP 11574) "nvim" 0x00007ffcec9e9c59 in clock_gettime ()

    (gdb) thread apply all  bt

    Thread 2 (Thread 0x7f761f5ff700 (LWP 11574)):
    #0  0x00007ffcec9e9c59 in clock_gettime ()
    #1  0x00007f76210b9356 in clock_gettime () from /usr/lib/libc.so.6
    #2  0x00007f7622513e3c in ?? () from /usr/lib/libuv.so.1
    #3  0x00007f7622505e94 in uv_run () from /usr/lib/libuv.so.1
    #4  0x00000000004822ed in loop_close (loop=loop@entry=0x7f761f5fe870) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/event/loop.c:87
    #5  0x00000000005a7ec0 in tui_main (bridge=0x7f761f6ac000, ui=0x7f761f69ace0) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/tui/tui.c:234
    #6  0x00000000005a9b47 in ui_thread_run (data=<optimized out>) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/ui_bridge.c:87
    #7  0x00007f7622510d07 in ?? () from /usr/lib/libuv.so.1
    #8  0x00007f76222e5474 in start_thread () from /usr/lib/libpthread.so.0
    #9  0x00007f76210ac69d in clone () from /usr/lib/libc.so.6

    Thread 1 (Thread 0x7f7622907780 (LWP 11567)):
    #0  0x00007f76222e66bd in pthread_join () from /usr/lib/libpthread.so.0
    #1  0x00007f7622510dae in uv_thread_join () from /usr/lib/libuv.so.1
    #2  0x00000000005aac9e in ui_bridge_stop (b=0x7f761f6ac000) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/ui_bridge.c:104
    #3  0x00000000005a90e4 in ui_builtin_stop () at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/ui.c:91
    #4  0x000000000052be09 in mch_exit (r=r@entry=1) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/os_unix.c:143
    #5  0x00000000004db1cc in getout (exitval=exitval@entry=1) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/main.c:623
    #6  0x00000000004fa43c in preserve_exit () at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/misc1.c:2652
    #7  0x000000000052b77a in deadly_signal (signum=1) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/os/signal.c:120
    #8  0x000000000052b7cf in on_signal (handle=<optimized out>, signum=<optimized out>, data=<optimized out>) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/os/signal.c:145
    #9  0x0000000000484178 in signal_event (argv=<optimized out>) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/event/signal.c:44
    #10 0x0000000000483b7f in queue_process_events (queue=0x7f7620417360) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/event/queue.c:142
    #11 0x0000000000482208 in loop_poll_events (loop=0x84dec0 <loop>, ms=ms@entry=4000) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/event/loop.c:56
    #12 0x000000000052a364 in input_poll (ms=ms@entry=4000) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/os/input.c:325
    #13 0x000000000052a3e2 in inbuf_poll (ms=4000) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/os/input.c:347
    #14 0x000000000052a839 in os_inchar (buf=buf@entry=0x0, maxlen=maxlen@entry=0, ms=ms@entry=-1, tb_change_cnt=tb_change_cnt@entry=0) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/os/input.c:107
    #15 0x0000000000592eeb in state_enter (s=s@entry=0x7ffcec9d3560) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/state.c:46
    #16 0x0000000000508533 in normal_enter (cmdwin=cmdwin@entry=false, noexmode=noexmode@entry=false) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/normal.c:464
    #17 0x00000000004dc17e in main (argc=<optimized out>, argv=<optimized out>) at /tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src/nvim/main.c:538

src/nvim/event/loop.c

@@ -76,7 +76,7 @@ void loop_on_put(Queue *queue, void *data)
   uv_stop(&loop->uv);
 }
 
-void loop_close(Loop *loop)
+void loop_close(Loop *loop, bool wait)
 {
   uv_mutex_destroy(&loop->mutex);
   uv_close((uv_handle_t *)&loop->children_watcher, NULL);
@@ -84,8 +84,8 @@ void loop_close(Loop *loop)
   uv_close((uv_handle_t *)&loop->poll_timer, NULL);
   uv_close((uv_handle_t *)&loop->async, NULL);
   do {
-    uv_run(&loop->uv, UV_RUN_DEFAULT);
+    uv_run(&loop->uv, wait ? UV_RUN_DEFAULT : UV_RUN_NOWAIT);
-  } while (uv_loop_close(&loop->uv));
+  } while (uv_loop_close(&loop->uv) && wait);
   queue_free(loop->fast_events);
   queue_free(loop->thread_events);
   queue_free(loop->events);

src/nvim/main.c

@@ -165,7 +165,7 @@ void event_teardown(void)
   signal_teardown();
   terminal_teardown();
 
-  loop_close(&main_loop);
+  loop_close(&main_loop, true);
 }
 
 /// Performs early initialization.

src/nvim/tui/tui.c

@@ -237,7 +237,7 @@ static void tui_main(UIBridgeData *bridge, UI *ui)
   signal_watcher_stop(&data->cont_handle);
   signal_watcher_close(&data->cont_handle, NULL);
   signal_watcher_close(&data->winch_handle, NULL);
-  loop_close(&tui_loop);
+  loop_close(&tui_loop, false);
   kv_destroy(data->invalid_regions);
   xfree(data);
   xfree(ui);