perf trace beauty open_flags: Add missing headers

perf trace beauty open_flags: Add missing headers

Those beautifiers need to make sure they include what they reference,
as changes in builtin-trace.c may end up removing needed stuff, like
when undefining _GNU_SOURCE.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-a9cz8za6lqutfapn5e7uum09@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>