Make secure-memory be a config option

Make secure-memory be a config option

Adding support for "no-secure-memory" was simple, a one-liner.
Fixing all the "ifdef OPENSSL_SECURE_MEMORY" to be "ifndef NO_xxx"
was a bit more work.  My original goof, for not following the OpenSSL
pattern "ifndef NO_" used everywhere else.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/11023)