This issue surfaced while I tried upgrading meson to version 0.51.0 - where a
new LLVM test suite has been added

The test validates that it makes no difference by what means one would interact
with llvm, i.e be it by querying llvm-config or using cmake. Sadly, only
openSUSE. said test fails with:

[  621s] meson.build:41:4: ERROR: Assert failed: RTTI information for cmake and
config tools disagree

And indeed, when inspecting the internas, one gets:

> llvm-config --has-rtti
YES

> grep RTTI /usr/lib64/cmake/llvm/LLVMConfig.cmake 
set(LLVM_ENABLE_RTTI OFF)

So in this case it would actually make a difference to the consumer if they
were to use cmake or llvm-config to detect what capabilities our LLVM8
provides. Certainly that is not meant to be like this.