InstCombine: Stop two transforms dueling

InstCombineMulDivRem has:
// Canonicalize (X+C1)*CI -> X*CI+C1*CI.

InstCombineAddSub has:
// W*X + Y*Z --> W * (X+Z)  iff W == Y

These two transforms could fight with each other if C1*CI would not fold
away to something simpler than a ConstantExpr mul.

The InstCombineMulDivRem transform only acted on ConstantInts until
r199602 when it was changed to operate on all Constants in order to
let it fire on ConstantVectors.

To fix this, make this transform more careful by checking to see if we
actually folded away C1*CI.

This fixes PR20079.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211258 91177308-0d34-0410-b5e6-96231b3b80d8
Remove OwningPtr.h and associated tests

llvm::OwningPtr is superseded by std::unique_ptr.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211259 91177308-0d34-0410-b5e6-96231b3b80d8
CommandLine: bail out when options get multiply registered

These errors are strictly unrecoverable and indicate serious issues such as
conflicting option names or an incorrectly linked LLVM distribution.

With this change, the errors actually get detected so tests don't pass
silently.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211260 91177308-0d34-0410-b5e6-96231b3b80d8