Make Tor support TLS1.3 ciphers with OpenSSL 1.1.1

Without this patch, not only will TLS1.3 not work with Tor, but
OpenSSL 1.1.1 with TLS1.3 enabled won't build any connections at
all: It requires that either TLS1.3 be disabled, or some TLS1.3
ciphersuites be listed.

Closes ticket 24978.