ARM: Implement big endian bit-conversion for NEON type

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208538 91177308-0d34-0410-b5e6-96231b3b80d8
[ARM64] Add proper bounds checking/diagnostics to logical shifts


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208540 91177308-0d34-0410-b5e6-96231b3b80d8