perf vendor events: Add support for arch standard events

For some architectures (like arm), there are architecture- defined
events. Sometimes these events may be "recommended" according to the
architecture standard, in that the implementer is free ignore the
"recommendation" and create its custom event.

This patch adds support for parsing standard events from arch-defined
JSONs, and fixing up vendor events when they have implemented these
events as standard.

Support is also ensured that the vendor may implement their own custom
events.

A new step is added to the pmu events parsing to fix up the vendor
events with the arch-standard events.

The arch-defined JSONs must be placed in the arch root folder for
preprocessing prior to tree JSON processing.

In the vendor JSON, to specify that the arch event is supported, the
keyword "ArchStdEvent" should be used, like this:

[
    {
        "ArchStdEvent": "L1D_CACHE_WR",
    },
]

Matching is based on the "EventName" field in the architecture JSON.

No other JSON objects are strictly required. However, for other objects
added, these take precedence over architecture defined standard events,
thus supporting separate events which have the same event code.

Signed-off-by: John Garry <john.garry@huawei.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shaokun Zhang <zhangshaokun@hisilicon.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: William Cohen <wcohen@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linuxarm@huawei.com
Link: http://lkml.kernel.org/r/1520506716-197429-8-git-send-email-john.garry@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>