Fix the Win32 VS2008 build:

Fix the Win32 VS2008 build:
 - Make type declarations match the struct/class keyword of the definition.
 - Move AddSignalHandler into the namespace where it belongs.
 - Correctly call functions from template base.
 - Some other small changes.
With this patch, LLVM and Clang should build properly and with far less noise under VS2008.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@67347 91177308-0d34-0410-b5e6-96231b3b80d8