Do not reference pthread_atfork under windows

Author: ogrisel

driver/others/memory.c

@@ -264,10 +264,12 @@ void openblas_fork_handler()
   //   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60035
   // In the mean time build with USE_OPENMP=0 or link against another
   // implementation of OpenMP.
+#ifndef OS_WINDOWS
   int err;
   err = pthread_atfork (BLASFUNC(blas_thread_shutdown), NULL, NULL);
   if(err != 0)
     openblas_warning(0, "OpenBLAS Warning ... cannot install fork handler. You may meet hang after fork.\n");
+#endif
 }
 
 int blas_get_cpu_number(void){