GitLab

The --header-only checks file header and prints the feature data.  But
as pipe mode doesn't have it in the header it prints almost nothing.
Change it to process first few records until it founds HEADER_FEATURE.

Before:
  $ perf record -o- true | perf report -i- --header-only
  # ========
  # captured on    : Thu Dec 10 14:34:59 2020
  # header version : 1
  # data offset    : 0
  # data size      : 0
  # feat offset    : 0
  # ========
  #

After:
  $ perf record -o- true | perf report -i- --header-only
  # ========
  # captured on    : Thu Dec 10 14:49:11 2020
  # header version : 1
  # data offset    : 0
  # data size      : 0
  # feat offset    : 0
  # ========
  #
  # hostname : balhae
  # os release : 5.7.17-1xxx
  # perf version : 5.10.rc6.gdb0ea13c
  # arch : x86_64
  # nrcpus online : 8
  # nrcpus avail : 8
  # cpudesc : Intel(R) Core(TM) i7-8665U CPU @ 1.90GHz
  # cpuid : GenuineIntel,6,142,12
  # total memory : 16158916 kB
  # cmdline : perf ...