This might not be of great help to you, but under Win32 strawberry-perl 5.16.3.1 #1 Tue Mar 12 12:12:07 2013 x64 the following code works:
use strict;
use Inline C => <<'__C__';
#include <stdio.h>
void test ( ) {
char buffer[] = { 'x' , 'y' , 'z' };
fwrite (buffer, 1, sizeof(buffer), stderr );
}
__C__
test( );
Reading your old thread, it looks to me that the root cause of the problem was a mismatch of compilers. So one solution could be to either change compilers or re-compile Perl with your preferred compiler.