clang-cl: Fix mangling of catchable types with names longer than 4kiB

The mangling used to contain the MD5 name of both the RTTI type
descriptor and the name of the copy ctor in MSVC2013, but it changed
to just the former in 2015. It looks like it changed back to the old
mangling in VS2017 version 15.7 and onwards, including VS2019 (version
16.0). VS2017 version 15.0 still has the VS2015 mangling. Versions
between 15.0 and 15.7 are't on godbolt. I found 15.4 (_MSC_VER 1911)
locally and that uses the 15.0 mangling still, but I didn't find 15.5 or
15.6, so I'm not sure where exactly it changed back.

Differential Revision: https://reviews.llvm.org/D62490

llvm-svn: 361959