Fix build for SDK on Mac

Change-Id: If99541e3537edbe3636e06b1766aa31d877a2fc8
diff --git a/core/jni/android_util_Process.cpp b/core/jni/android_util_Process.cpp
index 3f87574..07a7f22 100644
--- a/core/jni/android_util_Process.cpp
+++ b/core/jni/android_util_Process.cpp
@@ -267,12 +267,16 @@
 void android_os_Process_setThreadScheduler(JNIEnv* env, jclass clazz,
                                               jint tid, jint policy, jint pri)
 {
+#ifdef HAVE_SCHED_SETSCHEDULER
     struct sched_param param;
     param.sched_priority = pri;
     int rc = sched_setscheduler(tid, policy, &param);
     if (rc) {
         signalExceptionForPriorityError(env, errno);
     }
+#else
+    signalExceptionForPriorityError(env, ENOSYS);
+#endif
 }
 
 void android_os_Process_setThreadPriority(JNIEnv* env, jobject clazz,