BUILD: ssl: silence a warning reported for ERR_remove_state()

BUILD: ssl: silence a warning reported for ERR_remove_state()

In 1.0.0, this function was replaced with ERR_remove_thread_state().
As of openssl 1.1.0, both are now deprecated and do nothing at all.
Thus we simply make this call do nothing in 1.1.0 to silence the
warning.

The change was tested with 0.9.8, 1.0.0, 1.0.1, 1.0.2 and 1.1.0.

This kills the following warning on 1.1.0 :
   src/ssl_sock.c:7266:9: warning: 'ERR_remove_state' is deprecated (declared at /dev/shm/openssl-1.1.0b/include/openssl/err.h:247) [-Wdeprecated-declarations]

This fix should be backported to 1.7.