(atan2): For x <= 0, lump y == 0 with y > 0

to get the right result in 0, -1 case.

From-SVN: r4645

gcc/ginclude/math-68881.h

@@ -155,19 +155,19 @@ atan2 (double y, double x)
     }
   else
     {
-      if (y > 0)
+      if (y < 0)
 	{
-	  if (-x > y)
-	    return pi + atan (y / x);
+	  if (-x > -y)
+	    return - pi + atan (y / x);
 	  else
-	    return pi_over_2 - atan (x / y);
+	    return - pi_over_2 - atan (x / y);
 	}
       else
 	{
-	  if (-x > -y)
-	    return - pi + atan (y / x);
-	  else if (y < 0)
-	    return - pi_over_2 - atan (x / y);
+	  if (-x > y)
+	    return pi + atan (y / x);
+	  else if (y > 0)
+	    return pi_over_2 - atan (x / y);
 	  else
 	    {
 	      double value;