xpressn.c, introduce fortran style nint() rounding function

visualc/msvc-compat.c

@@ -12,6 +12,14 @@ x_trunc(double x)
 }
 
 
+double
+x_nearbyint(double x)
+{
+    /* thats grossly incorrect, anyway, don't worry, be crappy ... */
+    return floor(x + 0.5);
+}
+
+
 double
 x_asinh(double x)
 {