[sanitizer] Remove optional arguments from clone() invocation.

Unbreaks compilation on older systems. Patch by Andy Jost.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@186103 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc b/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
index fffd9bf..d8f3ca5 100644
--- a/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
+++ b/lib/sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cc
@@ -327,8 +327,8 @@
   // permissions.
   tracer_thread_argument.mutex.Lock();
   pid_t tracer_pid = clone(TracerThread, tracer_stack.Bottom(),
-                          CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_UNTRACED,
-                          &tracer_thread_argument, 0, 0, 0);
+                           CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_UNTRACED,
+                           &tracer_thread_argument);
   if (tracer_pid < 0) {
     Report("Failed spawning a tracer thread (errno %d).\n", errno);
     tracer_thread_argument.mutex.Unlock();