Remove register keyword usage.

Remove register keyword usage.

Add missing $DragonFly$ keyword to the following files:
src/lib/libc/db/btree/bt_utils.c
src/lib/libc/db/hash/hash_log2.c
src/lib/libc/net/getproto.c
src/lib/libc/net/getprotoent.c
src/lib/libc/net/getprotoname.c
src/lib/libc/net/getservbyname.c
src/lib/libc/net/getservbyport.c
src/lib/libc/net/iso_addr.c
src/lib/libc/net/linkaddr.c
src/lib/libc/net/ns_ntoa.c
src/lib/libc/quad/muldi3.c
src/lib/libc/quad/qdivrem.c
src/lib/libc/rpc/authdes_prot.c
src/lib/libc/rpc/key_prot_xdr.c
src/lib/libcompat/4.3/insque.c
src/lib/libcompat/4.3/lsearch.c
src/lib/libcompat/4.3/remque.c
src/lib/libcompat/4.4/cuserid.c
src/lib/libcompat/regexp/regexp.c
src/lib/libcompat/regexp/regsub.c
src/lib/libcr/db/btree/bt_utils.c
src/lib/libcr/db/hash/hash_log2.c
src/lib/libcr/net/getproto.c
src/lib/libcr/net/getprotoent.c
src/lib/libcr/net/getprotoname.c
src/lib/libcr/net/getservbyname.c
src/lib/libcr/net/getservbyport.c
src/lib/libcr/net/iso_addr.c
src/lib/libcr/net/linkaddr.c
src/lib/libcr/net/ns_ntoa.c
src/lib/libcr/quad/muldi3.c
src/lib/libcr/quad/qdivrem.c
src/lib/libcr/rpc/authdes_prot.c
src/lib/libcr/rpc/key_prot_xdr.c
src/lib/libedit/common.c
src/lib/libedit/emacs.c
src/lib/libipx/ipx_ntoa.c
src/lib/libm/common_source/fmod.c
src/lib/libstand/ether.c
src/lib/libstand/fstat.c
src/lib/libstand/gets.c
src/lib/libstand/ioctl.c
src/lib/libstand/netif.c
src/lib/libstand/rarp.c
src/lib/libstand/rpc.c
src/lib/libstand/strcasecmp.c
src/lib/libstand/strtol.c
src/lib/libstand/write.c