If SSL_clear is called before SSL_set_{connect,accept}_state (as SSL_new does
internally), s->state will get set prematurely. Likewise, s->server is set
based on the method's ssl_accept hook, but client SSL's may be initialized from
a generic SSL_METHOD too.

Since we can't easily get rid of the generic SSL_METHODs, defer s->state and
s->server initialization until the side is known.

Change-Id: I0972e17083df22a3c09f6f087011b54c699a22e7
Reviewed-on: https://boringssl-review.googlesource.com/2439
Reviewed-by: Adam Langley <agl@google.com>