Add fileno_unlocked to support thread sanitizer.

Bug: 25392375
Change-Id: If3f92a0e08a53f4b59e01397e8efa307d8572349
diff --git a/libc/libc.arm.map b/libc/libc.arm.map
index bc68fc0..b632d3b 100644
--- a/libc/libc.arm.map
+++ b/libc/libc.arm.map
@@ -1310,6 +1310,7 @@
     __pwrite_chk;
     __pwrite64_chk;
     __write_chk;
+    fileno_unlocked;
     getgrgid_r;
     getgrnam_r;
     preadv;