Change use of /data to /data/local/tmp.

The unistd fsync/fdatasync were changed to use /data from /.
Unfortunately, this directory is unreadable unless you are root, so
change this path to /data/local/tmp.

Bug: 28885777
(cherry picked from commit 7e53843f7b4c061920d1742c8e70a50509d83a53)

Change-Id: I14514e985af8039ab63ac2bcf890f8d04dd82ccb
diff --git a/tests/unistd_test.cpp b/tests/unistd_test.cpp
index fae28a6..0729013 100644
--- a/tests/unistd_test.cpp
+++ b/tests/unistd_test.cpp
@@ -397,7 +397,7 @@
   // The fd can even be a directory.
-  ASSERT_NE(-1, fd = open("/data", O_RDONLY));
+  ASSERT_NE(-1, fd = open("/data/local/tmp", O_RDONLY));
   EXPECT_EQ(0, fn(fd));