[InstSimplify] vector div/rem with any zero element in divisor is undef

[InstSimplify] vector div/rem with any zero element in divisor is undef

This was suggested as a DAG simplification in the review for rL297026 :
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20170306/435253.html
...but let's start with IR since we have actual docs for IR (LangRef).

Differential Revision:
https://reviews.llvm.org/D30665

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297390 91177308-0d34-0410-b5e6-96231b3b80d8