Lu, Xiaoyu1

Add UEFI target support

11

#### build.rs: ABI of rust UEFI target [x86_64-unknown-uefi](https://github.com/rust-lang/rust/blob/master/compiler/rustc_target/src/spec/x86_64_unknown_uefi.rs#L5) is like windows. So add an AsmTarget like windows and it also need preassemble. Currently must use Clang to compile c code...

Add support for verifying certificate chain with EKU

2

There is a use case[(spdm)]( https://www.dmtf.org/sites/default/files/standards/documents/DSP0274_1.2.0WIP.90.pdf#%5B%7B%22num%22%3A178%2C%22gen%22%3A0%7D%2C%7B%22name%22%3A%22XYZ%22%7D%2C0%2C615%2C0%5D) where Certificate Extended Key Usage(EKU) Oid is customized, and EndCertEntity is used to verify certificate chain with customized EKU. But the current EndCertEntity does...

swupd LLVM 12 support?

2

Any chance we can see LLVM12 add to swupd?