I kept getting confused among the __cxa_exception*, the _Unwind_Exception* and...

I kept getting confused among the __cxa_exception*, the _Unwind_Exception* and the void* to the thrown object.  So I've gone through these two files and attempted to institute a consistent variable naming scheme, and in a few instances, turned void* into a concrete* to have the type system help me out.  No change in functionality for this commit is intended.

llvm-svn: 148663