issue-693: enable futex usage on arm

This patch was contributed by user spotrh.

src/base/linux_syscall_support.h

@@ -83,7 +83,6 @@
  *      sys_fcntl(
  *      sys_fstat(
  *      sys_futex(
- *      sys_futex1(
  *      sys_getcpu(
  *      sys_getdents64(
  *      sys_getppid(

src/base/spinlock_linux-inl.h

@@ -51,15 +51,10 @@ static struct InitModule {
     int x = 0;
     // futexes are ints, so we can use them only when
     // that's the same size as the lockword_ in SpinLock.
-#ifdef __arm__
-    // ARM linux doesn't support sys_futex1(void*, int, int, struct timespec*);
-    have_futex = 0;
-#else
     have_futex = (sizeof (Atomic32) == sizeof (int) &&
-                  sys_futex(&x, FUTEX_WAKE, 1, 0) >= 0);
-#endif
+                  sys_futex(&x, FUTEX_WAKE, 1, NULL, NULL, 0) >= 0);
     if (have_futex &&
-        sys_futex(&x, FUTEX_WAKE | futex_private_flag, 1, 0) < 0) {
+        sys_futex(&x, FUTEX_WAKE | futex_private_flag, 1, NULL, NULL, 0) < 0) {
       futex_private_flag = 0;
     }
   }
@@ -85,7 +80,8 @@ void SpinLockDelay(volatile Atomic32 *w, int32 value, int loop) {
       tm.tv_nsec *= 16;  // increase the delay; we expect explicit wakeups
       sys_futex(reinterpret_cast<int *>(const_cast<Atomic32 *>(w)),
                 FUTEX_WAIT | futex_private_flag,
-                value, reinterpret_cast<struct kernel_timespec *>(&tm));
+                value, reinterpret_cast<struct kernel_timespec *>(&tm),
+                NULL, 0);
     } else {
       nanosleep(&tm, NULL);
     }
@@ -96,7 +92,8 @@ void SpinLockDelay(volatile Atomic32 *w, int32 value, int loop) {
 void SpinLockWake(volatile Atomic32 *w, bool all) {
   if (have_futex) {
     sys_futex(reinterpret_cast<int *>(const_cast<Atomic32 *>(w)),
-              FUTEX_WAKE | futex_private_flag, all? INT_MAX : 1, 0);
+              FUTEX_WAKE | futex_private_flag, all? INT_MAX : 1,
+              NULL, NULL, 0);
   }
 }