### Description
We are having cores when stopping the lb service if TLS is enabled.
### Troubleshooting
#### Debugging Data
``` Core was generated by `/usr/sbin/kamailio -f /etc/kamailio/lb/kamailio.cfg -P /var/run/kamailio/kamail'. Program terminated with signal SIGSEGV, Segmentation fault. #0 ossl_init_thread_stop (locals=0x7faaf4442d58) at ../crypto/init.c:332 332 ../crypto/init.c: No such file or directory. (gdb) bt full #0 ossl_init_thread_stop (locals=0x7faaf4442d58) at ../crypto/init.c:332 No locals. #1 0x00007faaf8d15234 in OPENSSL_cleanup () at ../crypto/init.c:400 currhandler = <optimized out> lasthandler = <optimized out> #2 0x00007fab014bb910 in ?? () from /lib/x86_64-linux-gnu/libc.so.6 No symbol table info available. #3 0x00007fab014bb96a in exit () from /lib/x86_64-linux-gnu/libc.so.6 No symbol table info available. #4 0x0000556782094615 in handle_sigs () at main.c:698 chld = <optimized out> chld_status = 0 memlog = <optimized out> __func__ = "handle_sigs" #5 0x000055678209aa05 in main_loop () at main.c:1747
```
#### Log Messages ``` lb[8618]: WARNING: tls [tls_init.c:704]: init_tls_h(): tls: openssl bug #1491 (crash/mem leaks on low memory) workaround enabled (on low memory tls operations will fail preemptively) with free memory thresholds 7340032 and 3670016 bytes ```
### Additional Information
* **Kamailio Version** - output of `kamailio -v`
``` This is NGCP version based on 4.4.6
kamailio -v version: kamailio 4.4.6 (x86_64/linux) becbde flags: STATS: Off, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB poll method support: poll, epoll_lt, epoll_et, sigio_rt, select. id: becbde compiled with gcc 6.3.0 ```
* **Operating System**:
``` Debian stretch Linux spce 4.9.0-3-amd64 #1 SMP Debian 4.9.30-2+deb9u2 (2017-06-26) x86_64 GNU/Linux libssl1.1 version 1.1.0f-3 ```