[X86] Add VP2INTERSECT instructions

Support intel AVX512 VP2INTERSECT instructions in clang

Patch by Xiang Zhang (xiangzhangllvm)

Differential Revision: https://reviews.llvm.org/D62367

llvm-svn: 362196
diff --git a/clang/docs/ClangCommandLineReference.rst b/clang/docs/ClangCommandLineReference.rst
index ddba3b1..ee58c2d 100644
--- a/clang/docs/ClangCommandLineReference.rst
+++ b/clang/docs/ClangCommandLineReference.rst
@@ -2639,6 +2639,8 @@
 
 .. option:: -mavx512vnni, -mno-avx512vnni
 
+.. option:: -mavx512vp2intersect, -mno-avx512vp2intersect
+
 .. option:: -mavx512vpopcntdq, -mno-avx512vpopcntdq
 
 .. option:: -mbmi, -mno-bmi