am 7198030f: This should fix the simulator build.

Merge commit '7198030fce4b54820a65a10d54fae18a1ab5df84'

* commit '7198030fce4b54820a65a10d54fae18a1ab5df84':
  This should fix the simulator build.
diff --git a/libs/utils/futex_synchro.c b/libs/utils/futex_synchro.c
index ba19520..ab48c69 100644
--- a/libs/utils/futex_synchro.c
+++ b/libs/utils/futex_synchro.c
@@ -28,6 +28,7 @@
 // This futex glue code is need on desktop linux, but is already part of bionic.
 #if !defined(HAVE_FUTEX_WRAPPERS)
 
+#include <unistd.h>
 #include <sys/syscall.h>
 typedef unsigned int u32;
 #define asmlinkage