Test relayd error message for a broken config file.
Explicitly include <openssl/opensslconf.h> in every file that references
an OPENSSL_NO_* define. This avoids relying on something else pulling it
in for us, plus it fixes several cases where the #ifndef OPENSSL_NO_XYZ is
never going to do anything, since OPENSSL_NO_XYZ will never defined, due
to the fact that opensslconf.h has not been included.

This also includes some miscellaneous sorting/tidying of headers.