Keep external/fio building now we have <sys/shm.h>.

Change-Id: I1d1e18aae7f880b1d3cf4fdda7e1c32e4f0e6503
diff --git a/os/os-android.h b/os/os-android.h
index 172ad9a..c002509 100644
--- a/os/os-android.h
+++ b/os/os-android.h
@@ -61,6 +61,8 @@
 #include <linux/shm.h>
 #define SHM_HUGETLB    04000
 
+#define shmid_ds shmid64_ds
+
 #include <stdio.h>
 #include <linux/ashmem.h>
 #include <sys/mman.h>