Allow to display time in perf debug output via new
debug_set_display_time function.

It will be used in perf daemon command to get verbose output into log
file.

The debug time format is:

  [2020-12-03 18:25:31.822152] affinity: SYS
  [2020-12-03 18:25:31.822164] mmap flush: 1
  [2020-12-03 18:25:31.822175] comp level: 0
  [2020-12-03 18:25:32.002047] mmap size 528384B

Committer notes:

Cast tod.tv_usec to long to avoid this problem:

    78    12.70 ubuntu:18.04-x-sparc64        : FAIL sparc64-linux-gnu-gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0

  util/debug.c: In function 'fprintf_time':
  util/debug.c:63:32: error: format '%lu' expects argument of type 'long unsigned int', but argument 4 has type '__suseconds_t {aka int}' [-Werror=format=]
    return fprintf(file, "[%s.%06lu] ", date, tod.tv_usec);
                              ~~~~^           ~~~~~~~~~~~
                              %06u
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Budankov <abudankov@huawei.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20210102220441.794923-4-jolsa@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>