perf inject: Keep some features sections from input file

perf inject overwrites feature sections with information from the current
machine. It makes more sense to keep original information that describes
the machine or software when perf record was run.

Example: perf.data from "Desktop" injected on "nuc11"

 Before:

  $ perf script --header-only -i perf.data-from-desktop | head -15
  # ========
  # captured on    : Thu May 19 09:55:50 2022
  # header version : 1
  # data offset    : 1208
  # data size      : 837480
  # feat offset    : 838688
  # hostname : Desktop
  # os release : 5.13.0-41-generic
  # perf version : 5.18.rc5.gac837f7ca7ed
  # arch : x86_64
  # nrcpus online : 28
  # nrcpus avail : 28
  # cpudesc : Intel(R) Core(TM) i9-9940X CPU @ 3.30GHz
  # cpuid : GenuineIntel,6,85,4
  # total memory : 65548656 kB

  $ perf inject -i perf.data-from-desktop -o injected-perf.data

  $ perf script --header-only -i injected-perf.data | head -15
  # ========
  # captured on    : Fri May 20 15:06:55 2022
  # header version : 1
  # data offset    : 1208
  # data size      : 837480
  # feat offset    : 838688
  # hostname : nuc11
  # os release : 5.17.5-local
  # perf version : 5.18.rc5.g0f828fdeb9af
  # arch : x86_64
  # nrcpus online : 8
  # nrcpus avail : 8
  # cpudesc : 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz
  # cpuid : GenuineIntel,6,140,1
  # total memory : 16012124 kB

 After:

  $ perf inject -i perf.data-from-desktop -o injected-perf.data

  $ perf script --header-only -i injected-perf.data | head -15
  # ========
  # captured on    : Fri May 20 15:08:54 2022
  # header version : 1
  # data offset    : 1208
  # data size      : 837480
  # feat offset    : 838688
  # hostname : Desktop
  # os release : 5.13.0-41-generic
  # perf version : 5.18.rc5.gac837f7ca7ed
  # arch : x86_64
  # nrcpus online : 28
  # nrcpus avail : 28
  # cpudesc : Intel(R) Core(TM) i9-9940X CPU @ 3.30GHz
  # cpuid : GenuineIntel,6,85,4
  # total memory : 65548656 kB

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20220520132404.25853-4-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>