perf parse: Provide a way to pass a fake_pmu to parse_events()

perf parse: Provide a way to pass a fake_pmu to parse_events()

This is an alternative patch to what Jiri sent that instead of changing
all callers to parse_events() for allowing to pass a fake_pmu, provide
another function specifically for that.

From Jiri's patch:

This way it's possible to parse events from PMUs which are not present
in the system. It's available only for testing purposes coming in
following changes, so all the current users set fake_pmu argument as
false.

Based-on-a-patch-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20200602214741.1218986-3-jolsa@kernel.org
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>