[X86][AVX512] Add support for v4i64 fptosi/fptoui/sitofp/uitofp on AVX512DQ-only targets

Use 512-bit instructions with subvector insertion/extraction like we do in a number of similar circumstances

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287762 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed