[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 815a9b2 [X86] Remove isSafeToClobberEFLAGS helper and just inline it into the call sites.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   815a9b2..48887c4  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to 48887c4e81d47ebeaa6dc7888143cc51bd0ed7c5.
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!