So that it can get rid of requirement of a compiler.
Also define and use more local symbols to ease future changes.

  $ sudo ./perf test -v pipe
   87: perf pipe recording and injection test                          :
  --- start ---
  test child forked, pid 748003
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
      748014   748014       -1 |perf
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
      99.83%  perf     perf                  [.] noploop
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.000 MB - ]
      99.85%  perf     perf                  [.] noploop
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.160 MB /tmp/perf.data.2XYPdw (4007 samples) ]
      99.83%  perf     perf                  [.] noploop
  test child finished with 0
  ---- end ----
  perf pipe recording and injection test: Ok
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: James Clark <james.clark@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zhengjun Xing <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20221116233854.1596378-3-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>