Rename Win64Exception.(cpp|h) to WinException.(cpp|h)

This is in preparation for reusing this for 32-bit x86 EH table
emission.  Also updates the type name for consistency. NFC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238521 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed