pgpool: Fix heartbeat device treatment.

Fix heartbeat device treatment.

wd_create_hb_recv_socket() and wd_create_hb_send_socket() called
setsockopt(2) with wrong argument.

struct ifreq i;
strlcpy(i.ifr_name, hb_if->if_name, sizeof(i.ifr_name));
if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, &i, sizeof(i)) == -1)
:

This is not quite correct since the 4th argument should be
just a null terminated string (device name), not struct ifreq.

Discussion: [pgpool-hackers: 4602] heartbeat and SO_BINDTODEVICE
https://www.pgpool.net/pipermail/pgpool-hackers/2025-May/004603.html
Backpatch-through: v4.6

Branch
------
V4_6_STABLE

Details
-------
https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=f88b1c18f68c9d57ddbf92499b8fedc01f26e52a

Modified Files
--------------
src/watchdog/wd_heartbeat.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)