llvm-c: Make LLVM{Get,Set}Alignment work on {Load,Store}Inst too

Patch by Peter Zotov

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



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193597 91177308-0d34-0410-b5e6-96231b3b80d8