[NaCl SDK] nacl_io: Enable isatty running under sel_ldr.

native_client_sdk/src/libraries/nacl_io/syscalls/isatty.c

Index: native_client_sdk/src/libraries/nacl_io/syscalls/isatty.c
diff --git a/native_client_sdk/src/libraries/nacl_io/syscalls/isatty.c b/native_client_sdk/src/libraries/nacl_io/syscalls/isatty.c
index f305f3fa40ec27464a0accade16ef3aa2ad8d941..8a5487397daf1994348f35c2fd0b8eec06741427 100644
--- a/native_client_sdk/src/libraries/nacl_io/syscalls/isatty.c
+++ b/native_client_sdk/src/libraries/nacl_io/syscalls/isatty.c
@@ -5,6 +5,11 @@
 #include "nacl_io/kernel_intercept.h"
 #include "nacl_io/kernel_wrap.h"
 
+#if !defined(__native_client__) || defined(__GLIBC__)
+// GLIBC-only entry point.
+// TODO(sbc): remove once this bug gets fixed:
+// https://code.google.com/p/nativeclient/issues/detail?id=3709
 int isatty(int fd) {
   return ki_isatty(fd);
 }
+#endif