perf evsel: Fallback to "task-clock" when not system wide

perf evsel: Fallback to "task-clock" when not system wide

When the "cycles" event isn't available evsel will fallback to the
"cpu-clock" software event.

"task-clock" is similar to "cpu-clock" but only runs when the process is
running.

Falling back to "cpu-clock" when not system wide leads to confusion, by
falling back to "task-clock" it is hoped the confusion is less.

Pass the target to determine if "task-clock" is more appropriate.

Update a nearby comment and debug string for the change.

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ajay Kaher <akaher@vmware.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Makhalov <amakhalov@vmware.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/r/20231121000420.368075-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>