[clang] Enabling Intel GPU Integration. (PR #65539)

[Jianhui Li via cfe-commits]

Jianhui-Li wrote:

@rengolin  @joker-eph  @Hardcode84  

FYI that this PR enables the current GPU dialect on Intel GPU as is, without introducing stream/queue to the current GPU dialect. 

https://github.com/llvm/llvm-project/pull/65539