Avoid usage of deprecated RoundingMode in BigDecimal

The setScale(...) method accepting the mode as integer has been
deprecated with Java 9. Given that Draw2D requires at least Java 17, we
can simply use the drop-in replacement via the RoundingMode enum.

Contributes to eclipse-gef#778

Author: ptziegler

org.eclipse.draw2d/src/org/eclipse/draw2d/geometry/PrecisionGeometry.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2010 itemis AG and others.
+ * Copyright (c) 2010, 2025 itemis AG and others.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
@@ -14,6 +14,7 @@
 package org.eclipse.draw2d.geometry;
 
 import java.math.BigDecimal;
+import java.math.RoundingMode;
 
 /**
  * A Utilities class for precise geometry calculations.
@@ -27,7 +28,7 @@ public class PrecisionGeometry {
 	 * Precise calculations on doubles are performed based on BigDecimals,
 	 * converting to 16 digits scale, so there are no undesired rounding effects.
 	 */
-	private static final int ROUNDING = BigDecimal.ROUND_HALF_EVEN;
+	private static final RoundingMode ROUNDING = RoundingMode.HALF_EVEN;
 	private static final int SCALE = 16;
 
 	protected static final double preciseAdd(double d1, double d2) {