Deprecate ERR_get_state()

Deprecate ERR_get_state()

Internally, we still need this function, so we make it internal and
then add a new ERR_get_state() that simply calls the internal variant,
unless it's "removed" by configuration.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9462)