[v6.x backport] src: guard bundled_ca/openssl_ca with HAVE_OPENSSL

This is a backport of the following PRs:

• https://github.com/nodejs/node/pull/12302
• https://github.com/nodejs/node/pull/12087

Please note that there was a previous PR for backporting this, but was closed as noted in this comment.

@MylesBorins I'm not sure if this should land due to your comment above. Could you take a look and let me know what you think?

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

Affected core subsystem(s)

src