AVX-512: Intrinsics for ERI
3 instructions: vrcp28, vrsqrt28, vexp2, only vector forms.
Intrinsics include SAE (Suppres All Exceptions) parameter.

http://reviews.llvm.org/D6214



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221774 91177308-0d34-0410-b5e6-96231b3b80d8