perf record: Fix event fd races

perf record: Fix event fd races

The write call may set errno which is problematic if occurring in a
function also setting errno. Save and restore errno around the write
call.

done_fd may be used after close, clear it as part of the close and check
its validity in the signal handler.

Suggested-by: <gthelen@google.com>
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Anand K Mistry <amistry@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20221024011024.462518-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>