perf stat: Fix JSON output in metric-only mode

It generated a broken JSON output when aggregation mode or cgroup is
used with --metric-only option.  Also get rid of the header line and
make the output single line for each entry.

It needs to know whether the current metric is the first one or not.
So add 'first' field in the outstate and mark it false after printing.

Before:

  # perf stat -a -j --metric-only true
  {"unit" : "GHz"}{"unit" : "insn per cycle"}{"unit" : "branch-misses of all branches"}
  {{"metric-value" : "0.797"}{"metric-value" : "1.65"}{"metric-value" : "0.89"}
   ^

  # perf stat -a -j --metric-only --per-socket true
  {"unit" : "GHz"}{"unit" : "insn per cycle"}{"unit" : "branch-misses of all branches"}
  {"socket" : "S0", "aggregate-number" : 8, {"metric-value" : "0.295"}{"metric-value" : "1.88"}{"metric-value" : "0.64"}
                                           ^

After:

  # perf stat -a -j --metric-only true
  {"GHz" : "0.990", "insn per cycle" : "2.06", "branch-misses of all branches" : "0.59"}

  # perf stat -a -j --metric-only --per-socket true
  {"socket" : "S0", "aggregate-number" : 8, "GHz" : "0.439", "insn per cycle" : "2.14", "branch-misses of all branches" : "0.51"}

Signed-off-by: Namhyung Kim <[email protected]>
Acked-by: Ian Rogers <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Athira Jajeev <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Clark <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Kan Liang <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Xing Zhengjun <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions