Add support for Android

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/backend.c b/backend.c
index b80c903..f901503 100644
--- a/backend.c
+++ b/backend.c
@@ -34,7 +34,9 @@
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <sys/ipc.h>
+#ifndef FIO_NO_HAVE_SHM_H
 #include <sys/shm.h>
+#endif
 #include <sys/mman.h>
 
 #include "fio.h"