add control point for unhandled fault

_From [bruen...@google.com](https://code.google.com/u/109494838902877177630/) on November 01, 2012 21:23:15_

currently we have a dumpcore point for all app faults:

```
/* Note this is ALL app exceptions (including those the app may expect and
* handle without issue) except those created via RaiseException (note
* dr forged exceptions use the eqv. of RaiseException). Would be nice to
* have a flag for just unhandled app exceptions but that's harder to
* implement. */
DUMPCORE_APP_EXCEPTION = 0x40000,
```

easy on linux to see if the app has a handler.
on windows we'll need to wait for ntcontinue or sthg.

we should also augment the ldmp format w/ a (symbolic) app callstack at the top.

we should also implement issue #397 to get tools/ldmp working on Vista+.

xref drmem issue #1015: https://code.google.com/p/drmemory/issues/detail?id=1015

_Original issue: http://code.google.com/p/dynamorio/issues/detail?id=966_