[NFC] use bit_cast in PointerSumType

The code was already using union and memcpy to do this. Remove the memcpy. We can't just change the union because a reference to its member is returned.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342759 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed