Building with gcc 8.2 against musl libc, which apparently has more attributes
available in its sched_param. The following warnings were produced:
warning: missing initializer for member 'sched_param::sched_ss_low_priority' [-Wmissing-field-initializers]
warning: missing initializer for member 'sched_param::sched_ss_repl_period' [-Wmissing-field-initializers]
warning: missing initializer for member 'sched_param::sched_ss_init_budget' [-Wmissing-field-initializers]
warning: missing initializer for member 'sched_param::sched_ss_max_repl' [-Wmissing-field-initializers]
Since the current thread may have interesting non-zero values for these fields,
we want to be sure to only change the intended one. Query and modify the
current sched_param rather than starting from a zeroed one.
In the config file, sections are specified by square bracket pair "[]"$,
or included in the option name itself which separated by a period"(.)".
Typicaly, [testnet] is not a correct section name and specified options
in that section are ignored but user cannot recognize what is happen.
So, add some log/stderr-warning messages if unrecognized section names
are present in the config file after checking section only args.