knot-resolver: enable dnstap module build by default
dnstap module will be built but not loaded by default at runtime
(configuration must be provided for it to be loaded). It is still possible to
disable dnstap build manually using menuconfig.
"The dnstap module supports logging DNS requests and responses to a unix socket in dnstap format using fstrm framing library. This logging is useful if you need effectively log all DNS traffic."1
Adds dependency on protobuf, protobuf-c, libfstrm. Listed packages are
available from OpenWrt packages, have uncomplicated manifests and
while protobuf-c doesn't have a maintainer since spring 2020, all the
packages (including protobuf-c) seem to be maintained - the last
updates of all of them in autumn 2021.
As stated by a Knot developer they build dnstap while packaging for
majority of standard Linux distributions. Therefore this change brings
us closer to expected default.
Testing done:
Was successfully built by the build server and run tested on Turris Omnia and Turris Mox on current HBL branch.