Is it possible to define the root directory in a cross compiled program

[Roger Kaufman]

When I cross compile the following program, opening /dev/null fails and 
instead the whole install path of /cygwin64/dev/null is visible.

Is there a way to make fopen respect / as the root directory in a cross 
compiled program for windows?

example output...

Roger@interocitor:~
$ x86_64-w64-mingw32-g++ -o writenull.exe write2null.cc

Roger@interocitor:~
$ writenull.exe
/dev/null did not succeed


Roger@interocitor:~
$ gcc -o writenull write2null.cc

Roger@interocitor:~
$ writenull
/cygwin64/dev/null did not succeed


C Code that was compiled...

#include <cstdio>

int main(int argc, char **argv)
{
   FILE *errfile1 = fopen("/dev/null", "w");
   if (!errfile1) // must be a valid pointer
     errfile1 = stderr;

   FILE *errfile2 = fopen("/cygwin64/dev/null", "w");
   if (!errfile2) // must be a valid pointer
     errfile2 = stderr;

   fprintf(errfile1, "/dev/null did not succeed\n");
   fprintf(errfile2, "/cygwin64/dev/null did not succeed\n");

   return 0;
}