[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at df12524 [X86] Turn X86DAGToDAGISel::tryVPTERNLOG into a fully custom instruction selector that can handle bitcasts between logic ops
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   df12524..8dc8203  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 8dc820393219c7ee440b4ec86c9a201301943276.
CMake Error at CMakeLists.txt:3 (cmake_minimum_required):
  CMake 3.13.4 or higher is required.  You are running version 3.7.1


-- Configuring incomplete, errors occurred!