NO QUEUING of SIGNAL ACTIONS

```
Description: In the architecture specific implementation of struct xcptcontext,
there are fields used by signal handling logic to pass the state
information needed to dispatch signal actions to the appropriate
handler.

There is only one copy of this state information in the
implementations of struct xcptcontext and, as a consequence,
if there is a signal handler executing on a thread, then addition
signal actions will be lost until that signal handler completes
and releases those resources.
Status: Open
Priority: Low. This design flaw has been around for ages and no one has yet
complained about it. Apparently the visibility of the problem is
very low.
```