clover: set LLVM min version to 8.0.1
It also bump from 8.0.0 to .1 for AMD gallium and VK
AMD driver and SPIRV are our main consumers. radeonsi already require LLVM>=8.0.0 and for SPIRV there is !5038 (merged) looking for a bump to 8.0.1. Let's use the opportunity to get ride of some clover comptat stuff
Edited by Serge Martin