[llvm] [llvm-config] Quote and escape paths (PR #97305)

[Mike Hommey via llvm-commits]

glandium wrote:

I gave one subtle example, but here's another one less subtle: https://github.com/AFLplusplus/AFLplusplus/blob/stable/GNUmakefile.llvm#L420 this simple straightforward use breaks completely (can't find includes when compiling).

https://github.com/llvm/llvm-project/pull/97305