This is probably something I haven't installed right, but could
you point me in the right direction?

$ sh run_example.sh daytime

causes the link error below. What library have I failed to
install?

NMS

(Abbreviated for your sanity)
Undefined symbols for architecture x8664:<br> "SSLCTXctrl", referenced from:

   _SSL_CTX_set_tlsext_servername_arg in daytime.d.o
   _SSL_CTX_get_tlsext_ticket_keys in daytime.d.o
   _SSL_CTX_set_tlsext_ticket_keys in daytime.d.o
   _SSL_CTX_set_tlsext_status_arg in daytime.d.o
   _SSL_CTX_set_tlsext_opaque_prf_input_callback_arg in 

daytime.d.o

D6deimos7openssl3ssl25T19SSLCTXsetoptionsZ19SSLCTXsetoptionsUNbPS6deimos7openssl3ssl10sslctxstlZl
in daytime.d.o
"SSLread", referenced from:

   _D4vibe6stream3ssl9SslStream4readMFAhZv in daytime.d.o

"SSLnew", referenced from:

D4vibe6crypto3ssl10SslContext15createClientCtxMFZPS6deimos7openssl3ssl6sslst
in daytime.d.o
"BIOfree", referenced from:

   _D4vibe6stream3ssl9SslStream6__dtorMFZv in daytime.d.o

"BIOsetexdata", referenced from:

   _BIO_set_app_data in daytime.d.o

"SSLv23client_method", referenced from:

D4vibe6crypto3ssl10SslContext6ctorMFE4vibe6crypto3ssl10SSLVersionZC4vibe6crypto3ssl10SslContext <br>in daytime.d.o<br> "BIO_new", referenced from:

D4vibe6stream3ssl9SslStream6_ctorMFC4vibe6stream6stream6StreamC4vibe6crypto3ssl10SslContextE4vibe6stream3ssl14SslStreamStateZC4vibe6stream3ssl9SslStream
in daytime.d.o