math: fix pow(0,-inf) to raise divbyzero flag

src/math/pow.c

@@ -143,7 +143,7 @@ double pow(double x, double y)
 				return 1.0;
 			else if (ix >= 0x3ff00000) /* (|x|>1)**+-inf = inf,0 */
 				return hy >= 0 ? y : 0.0;
-			else                       /* (|x|<1)**+-inf = 0,inf */
+			else if ((ix|lx) != 0)     /* (|x|<1)**+-inf = 0,inf if x!=0 */
 				return hy >= 0 ? 0.0 : -y;
 		}
 		if (iy == 0x3ff00000)    /* y is +-1 */

src/math/powf.c

@@ -90,7 +90,7 @@ float powf(float x, float y)
 			return 1.0f;
 		else if (ix > 0x3f800000)  /* (|x|>1)**+-inf = inf,0 */
 			return hy >= 0 ? y : 0.0f;
-		else                       /* (|x|<1)**+-inf = 0,inf */
+		else if (ix != 0)          /* (|x|<1)**+-inf = 0,inf if x!=0 */
 			return hy >= 0 ? 0.0f: -y;
 	}
 	if (iy == 0x3f800000)    /* y is +-1 */