Add the glibc-compatible d_fileno.

d_ino is the POSIX name, but glibc also offers d_fileno, and
that's what strace is using.

Change-Id: I3fadbe7a64700b42e78c7f4631620e864d43147b
diff --git a/libc/include/dirent.h b/libc/include/dirent.h
index 3b00645..129cdfa 100644
--- a/libc/include/dirent.h
+++ b/libc/include/dirent.h
@@ -53,6 +53,7 @@
   unsigned char    d_type;
   char             d_name[256];
 };
+#define d_fileno d_ino
 #define dirent64 dirent
 
 typedef struct DIR DIR;