libperf: Do not include non-UAPI linux/compiler.h header

libperf: Do not include non-UAPI linux/compiler.h header

Its just for that __packed define, so use it expanded as __attribute__((packed)),
like the other files in /usr/include do.

This was problem was preventing building the libperf examples on ALT
Linux and Fedora 35, fix it.

Reported-by: Vitaly Chikunov <vt@altlinux.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Dmitry Levin <ldv@altlinux.org
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lore.kernel.org/lkml/Y0lnpl2Ix7VljVDc@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>