Avoid duplicating symbols in legacy.a with some build options

Avoid duplicating symbols in legacy.a with some build options

If no-module or no-shared is used, the symbols from
libcrypto should not be duplicated in legacy.a

Also the BIGNUM functions are currently not needed
in legacy.a at all.

Fixes #20124

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20137)