MS ABI: Allow a nullptr_t exception to be caught by void * catch handler

MS ABI: Allow a nullptr_t exception to be caught by void * catch handler

A nullptr exception object can be caught by any pointer type catch
handler.  However, it is not possible to express this in the exception
info for the MS ABI.  As a middle ground, allow such exception objects
to be caught with pointer-to-void catch handlers.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@232069 91177308-0d34-0410-b5e6-96231b3b80d8