[clang] [PS4, PS5][Driver] Detangle --sysroot and -isysroot (PR #107410)

[Paul T Robinson via cfe-commits]

https://github.com/pogo59 approved this pull request.

LGTM, but pointed out the need for a test comment update (& replicate to the PS5 equivalent test).

https://github.com/llvm/llvm-project/pull/107410