Enable gtest SEH when building with clang-cl

Clang supports SEH well enough that this should work out of the box.  If
it doesn't, we'll hear about it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249766 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed