Fix a crash in v2i_IPAddrBlocks()

If an IP address prefix value is supplied that is too large then a crash
can result. v2i_IPAddrBlocks() should sanity check the prefix value, as
should X509v3_addr_add_prefix().

Reported by Theo Buehler (@botovq)

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/18523)