ptsname_r: Work around bug on Android 4.3. * m4/ptsname_r.m4 (gl_FUNC_PTSNAME_R): Define HAVE_ESSENTIALLY_WORKING_PTSNAME_R. Test whether the return value is correct. * lib/ptsname_r.c (__ptsname_r): If HAVE_ESSENTIALLY_WORKING_PTSNAME_R is defined, just fix the return value. * doc/glibc-functions/ptsname_r.texi: Mention the Android bug. Reword: The behaviour of musl libc is nothing to be "fixed", since it is compliant with the next POSIX standard.

# Suppress a valgrind message about use of uninitialized memory in memchr2().
# Like memchr, it is safe to overestimate the length when the terminator
# is guaranteed to be found.  In this case, we may end up reading a word
# that is partially uninitialized, but this use is OK for a speedup.
{
    memchr2-value4
    Memcheck:Value4
    fun:memchr2
}
{
    memchr2-value8
    Memcheck:Value8
    fun:memchr2
}