Remove obsolete dependency in dbaccess_parser.cc

src/lib/database/dbaccess_parser.cc has an obsolete (i.e. still compiles when it is removed and no obvious use in the code) dependency on dhcpsrv/parsers/dhcp_parsers.h. I propose to remove it as the database library is built before the dhcpsrv one.

BTW a comment in db_log.h needs to be updated too according to a grep dhcpsrv in the directory.