FixedNumOperandTraits and VariadicOperandTraits assumed that, given a

FixedNumOperandTraits and VariadicOperandTraits assumed that, given a
"this" pointer for any subclass of User, you could static_cast it to
User* and then reinterpret_cast that to Use* to get the end of the
operand list. This isn't a safe assumption in general, because the
static_cast might adjust the "this" pointer. Fixed by having these
OperandTraits classes take an extra template parameter, which is the
subclass of User. This is groundwork for PR889.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123235 91177308-0d34-0410-b5e6-96231b3b80d8