DirCache: Suppress resource warning related to TemporaryBuffer

In #writeTo, the TemporaryBuffer can't be opened in try-with-resource
because it's referenced in the finally block. Instead it is explicitly
closed within the try block. Suppress the warning with an explanatory
comment.

Change-Id: I02009f77f9630d5d55afc34eb86d304ff103b8b0
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit/src/org/eclipse/jgit/dircache/DirCache.java

@@ -702,6 +702,8 @@ public class DirCache {
 		}
 
 		if (writeTree) {
+			@SuppressWarnings("resource") // Explicitly closed in try block, and
+											// destroyed in finally
 			TemporaryBuffer bb = new TemporaryBuffer.LocalFile(dir, 5 << 20);
 			try {
 				tree.write(tmp, bb);