Added a new extension point to plug in custom utility to kill processes.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@31898 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/Proc.java

@@ -235,7 +235,7 @@ public abstract class Proc {
         /**
          * Destroys the child process without join.
          */
-        private void destroy() {
+        private void destroy() throws InterruptedException {
             ProcessTree.get().killAll(proc,cookie);
         }