crypto: remove BIO_set_shutdown

I've not been able to find any reason for calling
BIO_set_shutdown(bio, 1). This is done by default for the following
versions of OpenSSL:

https://github.com/openssl/openssl/blob/OpenSSL_1_1_0/
crypto/bio/bio_lib.c#L26

https://github.com/openssl/openssl/blob/OpenSSL_1_0_1/
crypto/bio/bio_lib.c#L90

https://github.com/openssl/openssl/blob/OpenSSL_1_0_2/
crypto/bio/bio_lib.c#L88

https://github.com/openssl/openssl/blob/OpenSSL_1_0_0/
crypto/bio/bio_lib.c#L90

This commit removes the call and the comment.

PR-URL: https://github.com/nodejs/node/pull/17542


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>