SoftGPU: Fix some minor rounding on viewport cull.

Had some tests failing when on the edge due to this.

GPU/Software/TransformUnit.cpp

@@ -104,16 +104,21 @@ static inline ScreenCoords ClipToScreenInternal(const ClipCoords& coords, bool *
 	float y = coords.y * yScale / coords.w + yCenter;
 	float z = coords.z * zScale / coords.w + zCenter;
 
+	// Account for rounding for X and Y.
+	const float SCREEN_BOUND = 4095.0f + (15.0f / 16.0f) + 0.375f;
+	// TODO: Validate actual rounding range.
+	const float DEPTH_BOUND = 65535.5f;
+
 	// This matches hardware tests - depth is clamped when this flag is on.
 	if (gstate.isDepthClampEnabled()) {
 		// Note: if the depth is clamped, the outside_range_flag should NOT be set, even for x and y.
 		if (z < 0.f)
 			z = 0.f;
-		else if (z > 65535.f)
-			z = 65535.f;
-		else if (outside_range_flag && (x > 4095.9375f || y > 4095.9375f || x < 0 || y < 0))
+		else if (z > 65535.0f)
+			z = 65535.0f;
+		else if (outside_range_flag && (x >= SCREEN_BOUND || y >= SCREEN_BOUND || x < 0 || y < 0))
 			*outside_range_flag = true;
-	} else if (outside_range_flag && (x > 4095.9375f || y > 4095.9375f || x < 0 || y < 0 || z < 0 || z > 65535.f)) {
+	} else if (outside_range_flag && (x > 4095.9675f || y >= SCREEN_BOUND || x < 0 || y < 0 || z < 0 || z >= DEPTH_BOUND)) {
 		*outside_range_flag = true;
 	}