perf tests x86 rdpmc: Add missing headers

Another case of a file using definitions and getting them by chance,
from indirect header inclusion, fix it.

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-o3l1vi4gw2w6xyc6z4ig938s@git.kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/x86/tests/rdpmc.c

+#include <errno.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <signal.h>
 #include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/wait.h>
 #include <linux/types.h>
 #include "perf.h"
 #include "debug.h"
 #include "tests/tests.h"
 #include "cloexec.h"
+#include "util.h"
 #include "arch-tests.h"
 
 static u64 rdpmc(unsigned int counter)