perf test bpf: Use epoll_wait() instead of epoll_pwait()

The prototype for epoll_wait() is available in older distros, so use it
instead of epoll_pwait() (removing the last NULL arg, the sigmask,
makes it the same thing anyway) to avoid breaking the build.

Cc: Adrian Hunter <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/bpf-script-example.c

···
 	.max_entries = 1,
 };
 
-SEC("func=sys_epoll_pwait")
-int bpf_func__sys_epoll_pwait(void *ctx)
+SEC("func=sys_epoll_wait")
+int bpf_func__sys_epoll_wait(void *ctx)
 {
 	int ind =0;
 	int *flag = bpf_map_lookup_elem(&flip_table, &ind);

tools/perf/tests/bpf.c

···
 
 #ifdef HAVE_LIBBPF_SUPPORT
 
-static int epoll_pwait_loop(void)
+static int epoll_wait_loop(void)
 {
 	int i;
 
 	/* Should fail NR_ITERS times */
 	for (i = 0; i < NR_ITERS; i++)
-		epoll_pwait(-(i + 1), NULL, 0, 0, NULL);
+		epoll_wait(-(i + 1), NULL, 0, 0);
 	return 0;
 }
 
···
 		"[basic_bpf_test]",
 		"fix 'perf test LLVM' first",
 		"load bpf object failed",
-		&epoll_pwait_loop,
+		&epoll_wait_loop,
 		(NR_ITERS + 1) / 2,
 	},
 #ifdef HAVE_BPF_PROLOGUE