stdio: use __REDIRECT for fwrite, fwrite_unlocked * lib/stdio.in.h (fwrite): When working around bug 11959, use __REDIRECT rather than '#define fwrite(...) ... fwrite (...) ...'. This is a more-targeted way to fix the -Wunused-value issue with clang, and it works with GCC too. Problem with targeting reported by Eric Blake in <http://lists.gnu.org/archive/html/bug-gnulib/2013-05/msg00067.html>. (fwrite_unlocked): Treat like fwrite. I ran into this issue while debugging the fwrite issue.

# Suppress a valgrind message about use of uninitialized memory in strchrnul().
# This use is OK because it provides only a speedup.
{
    strchrnul-value4
    Memcheck:Value4
    fun:strchrnul
}
{
    strchrnul-value8
    Memcheck:Value8
    fun:strchrnul
}