RecursiveMerger: fix boxing warning

Change-Id: I6f6ae540b128ff6b965931e829da1368a8b88ddb

org.eclipse.jgit/src/org/eclipse/jgit/merge/RecursiveMerger.java

@@ -249,7 +249,7 @@ private String failingPathsMessage() {
 
 		if (failingPaths.size() > max) {
 			failedPaths = String.format("%s\n... (%s failing paths omitted)", //$NON-NLS-1$
-					failedPaths, failingPaths.size() - max);
+					failedPaths, Integer.valueOf(failingPaths.size() - max));
 		}
 		return failedPaths;
 	}