[clang] [Driver] Add toolchain for X86_64 UEFI target (PR #76838)

[Pranav Bhandarkar via cfe-commits]

bhandarkar-pranav wrote:

Hi @Prabhuk, 
I am seeing this issue https://github.com/llvm/llvm-project/issues/109328 after this PR. Here is a proposed [fix](https://github.com/llvm/llvm-project/pull/109329). Could you please check?

https://github.com/llvm/llvm-project/pull/76838