[www-scripts] Clang Attribute Doc Update: ERROR

[root via www-scripts]

UPDATING LLVM SOURCES
HEAD is now at 64516ec [X86] Use parity flag from byte test/cmp instruction for __builtin_parity when input fits in 8 bits.
>From https://github.com/llvm/llvm-project
 * branch            master     -> FETCH_HEAD
   64516ec..e6c2c9a  master     -> origin/master
First, rewinding head to replay your work on top of it...
Fast-forwarded master to e6c2c9a7d15171a57c98024511eaa8885f1bd5fd.
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!