llvm 13 - missing part of update

[0-wiz-0]

When the supported version was increased to 13, the default in CMakeLists.txt was not bumped.
Please change 12 to 13 in

opencl-clang/CMakeLists.txt

Line 23 in e0d718e

set(PREFERRED_LLVM_VERSION "12.0.0")

Thanks.

[fzou1]

Thanks you. Created PR #298

[fzou1]

Merged PR #298. Closed.