odhcpd: update to Git HEAD (2025-10-02)

odhcpd: update to Git HEAD (2025-10-02)

b14cf98 router: log “Sending a RA on lan” at LOG_DEBUG
c2810fe odhcpd: update cmake file
8c2c065 odhcpd: convert README to markdown
3b96480 odhcpd: allow the use of an alternative cfg file
7328bfe odhcpd: remove confusing #defines
cdb9e5b odhcpd: improve RFC9096 § 3.5 SLAAC compliance

RFC9096 § 3.5 SLAAC compliance introduces a new config option (odhcpd
piofolder), which may wear out the flash under certain conditions (for
example: ISPs with dynamic IPv6 prefixes which disconnect the clients
every X hours).
Therefore, setting "dhcp.odhcpd.piofolder" to persistent storage in the
router flash is not advisable and should be set to other kinds of
persistent storage such as USBs, SDs, NVMEs...
In order to prevent wearing out the router flash it's set to ephemeral
storage by default (tmp):
  uci set dhcp.odhcpd.piofolder="/tmp/odhcpd-piofolder"

Signed-off-by: Álvaro Fernández Rojas <[email protected]>
(cherry picked from commit ea79b5875af8ead522050d16850264b01166e8a8)