Implement funopen64.

Bug: http://b/24807045
Change-Id: I161920978161389be34b707cc6ce8e05f760d552
diff --git a/libc/libc.arm.map b/libc/libc.arm.map
index df8030f..536273d 100644
--- a/libc/libc.arm.map
+++ b/libc/libc.arm.map
@@ -1233,6 +1233,7 @@
     freeifaddrs;
     fseeko64;
     fsetpos64;
+    funopen64;
     getgrgid_r;
     getgrnam_r;
     getifaddrs;