[PATCH bpf-next 3/3] selftests/bpf: Check __ARCH_WANT_SET_GET_RLIMIT before syscall(__NR_getrlimit)

[Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>]

__NR_getrlimit is defined only if __ARCH_WANT_SET_GET_RLIMIT is defined:

  #ifdef __ARCH_WANT_SET_GET_RLIMIT
  /* getrlimit and setrlimit are superseded with prlimit64 */
  #define __NR_getrlimit 163
  ...
  #endif

Some archs do not define __ARCH_WANT_SET_GET_RLIMIT, it should check
__ARCH_WANT_SET_GET_RLIMIT before syscall(__NR_getrlimit) to fix the
following build error:

    TEST-OBJ [test_progs] user_ringbuf.test.o
  tools/testing/selftests/bpf/prog_tests/user_ringbuf.c: In function 'kick_kernel_cb':
  tools/testing/selftests/bpf/prog_tests/user_ringbuf.c:593:17: error: '__NR_getrlimit' undeclared (first use in this function)
    593 |         syscall(__NR_getrlimit);
        |                 ^~~~~~~~~~~~~~
  tools/testing/selftests/bpf/prog_tests/user_ringbuf.c:593:17: note: each undeclared identifier is reported only once for each function it appears in
  make: *** [Makefile:573: tools/testing/selftests/bpf/user_ringbuf.test.o] Error 1
  make: Leaving directory 'tools/testing/selftests/bpf'

Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
---
 tools/testing/selftests/bpf/prog_tests/user_ringbuf.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/user_ringbuf.c b/tools/testing/selftests/bpf/prog_tests/user_ringbuf.c
index 3a13e10..0550307 100644
--- a/tools/testing/selftests/bpf/prog_tests/user_ringbuf.c
+++ b/tools/testing/selftests/bpf/prog_tests/user_ringbuf.c
@@ -590,7 +590,9 @@ static void *kick_kernel_cb(void *arg)
 	/* Kick the kernel, causing it to drain the ring buffer and then wake
 	 * up the test thread waiting on epoll.
 	 */
+#ifdef __ARCH_WANT_SET_GET_RLIMIT
 	syscall(__NR_getrlimit);
+#endif
 
 	return NULL;
 }
-- 
2.1.0