Repository: deno
Issue: Segmentation fault at exit
Labels: bug,FFI

Project running under Deno 1.15.3 on Linux x64 will segfault at exit.

The stack trace is:
```
#0  0x00007ffff0f8e210 in ?? ()
#1  0x00007ffff7596408 in __nptl_deallocate_tsd () at pthread_create.c:300
#2  0x00007ffff759781b in __nptl_deallocate_tsd () at ../sysdeps/nptl/futex-internal.h:200
#3  start_thread (arg=0x7ffff15f5700) at pthread_create.c:473
#4  0x00007ffff6f2271f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
```

Thread list
```
(gdb) info threads
  Id   Target Id         Frame
  1    Thread 0x7ffff7fdeb40 (LWP 20620) "deno" 0x00007ffff7598d2d in __GI___pthread_timedjoin_ex (threadid=140737242945280, thread_return=0x0, abstime=0x0, block=<optimized out>) at pthread_join_common.c:89
  2    Thread 0x7ffff6e00700 (LWP 20621) "V8 DefaultWorke" 0x00007ffff759dad3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555558ff117c) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
  3    Thread 0x7ffff65ff700 (LWP 20622) "V8 DefaultWorke" 0x00007ffff759dad3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555558ff117c) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
  4    Thread 0x7ffff5dfe700 (LWP 20623) "V8 DefaultWorke" 0x00007ffff759dad3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555558ff117c) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
  5    Thread 0x7ffff55fd700 (LWP 20624) "V8 DefaultWorke" 0x00007ffff759dad3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555558ff117c) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
  6    Thread 0x7ffff4dfc700 (LWP 20625) "V8 DefaultWorke" 0x00007ffff759dad3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555558ff117c) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
  7    Thread 0x7ffff45fb700 (LWP 20626) "V8 DefaultWorke" 0x00007ffff759dad3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555558ff117c) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
  8    Thread 0x7ffff3dfa700 (LWP 20627) "V8 DefaultWorke" 0x00007ffff759dad3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555558ff117c) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
  9    Thread 0x7ffff35f9700 (LWP 20628) "V8 DefaultWorke" 0x00007ffff759dad3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555558ff117c) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
  10   Thread 0x7ffff2df8700 (LWP 20629) "V8 DefaultWorke" 0x00007ffff759dad3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555558ff117c) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
  11   Thread 0x7ffff25f7700 (LWP 20630) "V8 DefaultWorke" 0x00007ffff759dad3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555558ff117c) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
  12   Thread 0x7ffff1df6700 (LWP 20631) "V8 DefaultWorke" 0x00007ffff759dad3 in futex_wait_cancelable (private=<optimized out>, expected=0, futex_word=0x555558ff117c) at ../sysdeps/unix/sysv/linux/futex-internal.h:88
* 13   Thread 0x7ffff15f5700 (LWP 20632) "tokio-runtime-w" 0x00007ffff0f8e210 in ?? ()
  14   Thread 0x7ffff0e0f700 (LWP 20633) "tokio-runtime-w" 0x00007ffff0f8e210 in ?? ()
```

Project is using non-blocking FFI