[LLVM-C] Add LLVMInstructionClone.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220007 91177308-0d34-0410-b5e6-96231b3b80d8
[OCaml] Add Llvm.instr_clone.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220008 91177308-0d34-0410-b5e6-96231b3b80d8