Hopefully fix the build.

Change-Id: Id8cd92c0895c9939e1386ef488bd1309a3be3568
diff --git a/libs/utils/Threads.cpp b/libs/utils/Threads.cpp
index c8de1f5..e5ece8e 100644
--- a/libs/utils/Threads.cpp
+++ b/libs/utils/Threads.cpp
@@ -281,6 +281,7 @@
 #endif
 }
 
+#if defined(HAVE_PTHREADS)
 static pthread_once_t gDoSchedulingGroupOnce = PTHREAD_ONCE_INIT;
 static bool gDoSchedulingGroup = true;
 
@@ -294,6 +295,7 @@
         }
     }
 }
+#endif
 
 int androidSetThreadSchedulingGroup(pid_t tid, int grp)
 {