llvm.memcpy.* has two distinct associated address spaces; the source address...

llvm.memcpy.* has two distinct associated address spaces; the source address space, and the destination address space.  Fix up the interface on MemIntrinsic and MemTransferInst to make this clear, and fix InstructionDereferencesPointer in LazyValueInfo.cpp to use the interface properly.

llvm-svn: 132356