src/node.cc: fix OpenSSL build error

Since version 0.10.33 (commit d601c76f4d728dd7adfa2fbbed2fe86de2e6b479) building nodejs without OpenSSL is broken. This issue is already reported upstream: https://github.com/joyent/node/issues/8676.

This issue is fixed by this patch.

Signed-off-by: Jörg Krause <jkrause@posteo.de>