fix arm64 build

arm64 doesn't have __NR__sysctl defined because the sysctl
syscall is deprecated.  Since the vulnerability being tested
for only applies to arm, wrap the entire test in #ifdef __arm__.

Bug: 15408470
Change-Id: I2bef16aca21f5d9757ff02ee92ae86c9157615c9
diff --git a/tests/tests/security/jni/android_security_cts_NativeCodeTest.cpp b/tests/tests/security/jni/android_security_cts_NativeCodeTest.cpp
index 73ca50c..dde06a2 100644
--- a/tests/tests/security/jni/android_security_cts_NativeCodeTest.cpp
+++ b/tests/tests/security/jni/android_security_cts_NativeCodeTest.cpp
@@ -174,6 +174,7 @@
  */
 static jboolean android_security_cts_NativeCodeTest_doVrootTest(JNIEnv*, jobject)
 {
+#ifdef __arm__
     ALOGE("Starting doVrootTest");
 
     struct __sysctl_args args;
@@ -188,6 +189,9 @@
 
     int result = syscall(__NR__sysctl, &args);
     return ((result == -1) && (errno == EFAULT));
+#else
+    return true;
+#endif
 }
 
 static void* mmap_syscall(void* addr, size_t len, int prot, int flags, int fd, off_t offset)