Add <stdio_ext.h> for elfutils.

Bug: 17139679
Change-Id: I1605ac382dbb6f23b2d874dbb9769f3cde4a6a99
diff --git a/libc/include/stdio.h b/libc/include/stdio.h
index 516f8cb..8727a9f 100644
--- a/libc/include/stdio.h
+++ b/libc/include/stdio.h
@@ -343,6 +343,11 @@
 int	 vasprintf(char ** __restrict, const char * __restrict,
     __va_list)
 		__printflike(2, 0);
+
+void clearerr_unlocked(FILE*);
+int feof_unlocked(FILE*);
+int ferror_unlocked(FILE*);
+
 __END_DECLS
 
 /*