Syncrepl code cleanup (namely prefix struct field names)

servers/slapd/add.c

servers/slapd/back-bdb/add.c

servers/slapd/back-bdb/ctxcsn.c

servers/slapd/back-bdb/delete.c

servers/slapd/back-bdb/modify.c

servers/slapd/back-bdb/modrdn.c

servers/slapd/back-ldbm/delete.c

servers/slapd/back-ldbm/modify.c

servers/slapd/back-ldbm/modrdn.c

servers/slapd/back-meta/cache-merge.c

servers/slapd/backend.c

servers/slapd/config.c

servers/slapd/delete.c

servers/slapd/modify.c

servers/slapd/modrdn.c

servers/slapd/passwd.c

servers/slapd/slap.h

servers/slapd/syncrepl.c