CodeGen: ubsan is built static on windows, give handlers local storage

The UBSAN runtime is built static on Windows.  This requires that we give local
storage always.  This impacts Windows where the linker would otherwise have to
generate a thunk to access the symbol via the IAT.  This should repair the
windows clang build bots.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@289829 91177308-0d34-0410-b5e6-96231b3b80d8