libcrypto: link engines and the legacy provider to libcrypto

OpenSSL's legacy provider module and engines need to link to
libcrypto.so, as it provides some of the actual implementations of
legacy routines.

This is a little tricky due to build order issues. Introduce a small
hack (LIBCRYPTO_WITHOUT_SUBDIRS) that builds libcrypto.so in its usual
early phase without any OpenSSL provider modules or engines. This is
intended to restore the test suite; a future change should remove the
hack and replace it with a better approach.

PR: 254853, 273528
Discussed with: Folks at EuroBSDCon in Coimbra
Sponsored by: The FreeBSD Foundation