[Clang][avx512][builtin] Adding intrinsics for vexpand{d|q|ps|pd} instrctuon set

Differential Revision: http://reviews.llvm.org/D19467



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@268214 91177308-0d34-0410-b5e6-96231b3b80d8