Move SSL_CTX sessionContext initialization into main SSL_CTX initialization path

Summary: This field was only previously set if setupSessionCache was called on the wangle::ServerSSLContext

Reviewed By: yfeldblum

Differential Revision: D5776057

fbshipit-source-id: ecdbe83816fee2ecbe7ea1b26a67b682a571309a

folly/io/async/SSLContext.cpp

@@ -573,8 +573,7 @@ void SSLContext::setSessionCacheContext(const std::string& context) {
       ctx_,
       reinterpret_cast<const unsigned char*>(context.data()),
       std::min<unsigned int>(
-          static_cast<unsigned int>(context.length()),
-          SSL_MAX_SSL_SESSION_ID_LENGTH));
+          static_cast<unsigned int>(context.length()), SSL_MAX_SID_CTX_LENGTH));
 }
 
 /**