Merge branch 'rate-size-parsing-output' into next

Petr Machata says:
==================

The DCB tool will have commands that deal with buffer sizes and traffic
rates. TC is another tool that has a number of such commands, and functions
to support them: get_size(), get_rate/64(), s/print_size() and
s/print_rate(). In this patchset, these functions are moved from TC to lib/
for possible reuse and modernized.

s/print_rate() has a hidden parameter of a global variable use_iec, which
made the conversion non-trivial. The parameter was made explicit,
print_rate() converted to a mostly json_print-like function, and
sprint_rate() retired in favor of the new print_rate. Patches #1 and #2
deal with this.

The intention was to treat s/print_size() similarly, but unfortunately two
use cases of sprint_size() cannot be converted to a json_print-like
print_size(), and the function sprint_size() had to remain as a discouraged
backdoor to print_size(). This is done in patch #3.

Patch #4 then improves the code of sprint_size() a little bit.

Patch #5 fixes a buglet in formatting small rates in IEC mode.

Patches #6 and #7 handle a routine movement of, respectively,
get_rate/64() and get_size() from tc to lib.

This patchset does not actually add any new uses of these functions. A
follow-up patchset will add subtools for management of DCB buffer and DCB
maxrate objects that will make use of them.

====================

Signed-off-by: David Ahern <dsahern@gmail.com>