Use syscall(2) instead of ioprio_get/ioprio_set.

Change-Id: Ibfd0bdd3dd0bad9804ec9fd9292f4b68a510afdb
diff --git a/libcutils/iosched_policy.c b/libcutils/iosched_policy.c
index 67e101d..3e80cb2 100644
--- a/libcutils/iosched_policy.c
+++ b/libcutils/iosched_policy.c
@@ -19,33 +19,21 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/syscall.h>
 #include <unistd.h>
 
-#ifdef HAVE_SCHED_H
-
 #include <cutils/iosched_policy.h>
 
 #ifdef HAVE_ANDROID_OS
-/* #include <linux/ioprio.h> */
-extern int ioprio_set(int which, int who, int ioprio);
-extern int ioprio_get(int which, int who);
+#include <linux/ioprio.h>
 #define __android_unused
 #else
 #define __android_unused __attribute__((__unused__))
 #endif
 
-enum {
-    WHO_PROCESS = 1,
-    WHO_PGRP,
-    WHO_USER,
-};
-
-#define CLASS_SHIFT 13
-#define IOPRIO_NORM 4
-
 int android_set_ioprio(int pid __android_unused, IoSchedClass clazz __android_unused, int ioprio __android_unused) {
 #ifdef HAVE_ANDROID_OS
-    if (ioprio_set(WHO_PROCESS, pid, ioprio | (clazz << CLASS_SHIFT))) {
+    if (syscall(SYS_ioprio_set, IOPRIO_WHO_PROCESS, pid, ioprio | (clazz << IOPRIO_CLASS_SHIFT))) {
         return -1;
     }
 #endif
@@ -56,11 +44,11 @@
 #ifdef HAVE_ANDROID_OS
     int rc;
 
-    if ((rc = ioprio_get(WHO_PROCESS, pid)) < 0) {
+    if ((rc = syscall(SYS_ioprio_get, IOPRIO_WHO_PROCESS, pid)) < 0) {
         return -1;
     }
 
-    *clazz = (rc >> CLASS_SHIFT);
+    *clazz = (rc >> IOPRIO_CLASS_SHIFT);
     *ioprio = (rc & 0xff);
 #else
     *clazz = IoSchedClass_NONE;
@@ -68,5 +56,3 @@
 #endif
     return 0;
 }
-
-#endif /* HAVE_SCHED_H */