perf jevents: Add support for parsing uncore json files

perf jevents: Add support for parsing uncore json files

Handle the "Unit" field, which is needed to find the right PMU for an
event. We call it "pmu" and convert it to the perf pmu name with an
uncore prefix.

Handle the "ExtSel" field, which just extends the event mask with an
additional bit.

Handle the "Filter" field which adds parameters to the main event
to configure filtering.

Handle the "Unit" field which declares the unit the values should be
scaled too (similar to what the kernel exports)

Set up the "perpkg" field for uncore events so that perf knows they are
per package (similar to what the kernel exports)

Then output the fields into the pmu-events data structures which are
compiled into perf.

Filter out zero fields, except for the event itself.

v2: Fix compilation. Add uncore_ prefix at pre-processing time.
    Move eventcode change to separate patch.

v3: Remove extra __maybe_unused

v4: dont duplicate aliases for cpu pmu events

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20170128020345.19007-3-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>