[PATCH] C API: implement LLVM{Get,Set}InstructionAlignment

[Anders Waldenborg]

  Some functions are overloaded to handle different Value types. e.g LLVMGetOperand which handles both MDNode and User. So it should be possible to extend LLVM{Get,Set}Alignment to handle load/store alignment.

  But it may be clearer using separate functions. Not sure.

http://llvm-reviews.chandlerc.com/D1910