[pool] advertising unchecked exceptions

[Phil Steitz]

I am going through now and comparing diffs of 2.11.1 and head of 2.x to
make sure that me and sed did not do anything wrong and I am seeing a bunch
of things like this:

-    void addObject() throws Exception, IllegalStateException,
-            UnsupportedOperationException;
+    void addObject() throws Exception;

Where the new version is the 2.x code.  I am inclined to leave as is, maybe
adding comments in some places indicating when the unchecked exceptions
might be thrown.  Any objections?

Phil