Reuse compression hint for RRSIGs. Optimizations.

src/common/mempattern.c

src/knot/dnssec/nsec-chain.c

src/knot/dnssec/zone-sign.c

src/knot/nameserver/internet.c

src/knot/nameserver/nsec_proofs.c

src/knot/nameserver/process_query.c

src/knot/nameserver/process_query.h

src/knot/zone/semantic-check.c

src/libknot/dnssec/rrset-sign.c

src/libknot/rrset.c

src/libknot/rrset.h