### Why I did it
We're not adding any patch on top of hiredis, and there's no apparent reason to build this. Remove the build step here, and just install the package from the Debian repos.
##### Work item tracking
- Microsoft ADO **(number only)**: 24381590
#### How to verify it
Build the SONiC image, and load it. Verify that services come up.
Enable dbgsym package for dhcpmon.
Allow CFLAGS and LDFLAGS from environment variables to be used
in the dhcp6relay build. This makes sure that the -O2 flag from
dpkg-buildflags gets used.
Finally, enable all hardening flags in dpkg-buildflags for
dhcp6relay and dhcpmon. The change from the default set of flags is that
during linking, immediate binding of symbols is done instead of lazy
binding.
Signed-off-by: Saikrishna Arcot <sarcot@microsoft.com>
DHCP relay MONitor (dhcpmon) keeps track of DORA messages. If DHCP Relay
is detected to be not forwarding DORA message, dhcpmon will log such event
to syslog. Under the hood dhcpmon keeps counts of clients DR messages,
forwarded DR messages, DHCP server OA messages, and forwarded OA messages.
dhcpmon will check every 12 sec (configurable) if counts are monotonically
increasing and record snapshot of those counters. dhcpmon will report
discrepancies when detected between current counters and snapshot counters.
pull-request: https://github.com/Azure/sonic-buildimage/pull/3886
signed-off-by: Tamer Ahmed <tamer.ahmed@microsoft.com>
