ARM: fix CodeGen for 64-bit shifts.

ARM: fix CodeGen for 64-bit shifts.

One half of the shifts obviously needed conditional selection based on whether
the shift amount is more than 32-bits, but leaving the other half as the
natural shift isn't acceptable either: it's undefined behaviour to shift a
32-bit value by more than 31.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287149 91177308-0d34-0410-b5e6-96231b3b80d8