[boost] [exception] patches for a few testing-related issues

Hi Emil, I have opened two Trac tickets (6877 and 6878) related to what I believe is a bug in exception_ptr_test.cpp and also for a minor change to the testing jamfile that will allow some of the thread-dependent tests to run on platforms that do not have automatic thread-specific-storage cleanup implemented (WinCE falls in this category). Are you ok with me applying these patches? Thanks, -Dave