fix: remove the check of lld not supporting @response-file In LLVM v9, lld has supported `@response-file.` LLVM v9 was released on 2019-09-19. The check was added back to 2018-03-14 (1.26.0) via04442af18b. It has been more than five years, and we ship our own lld regardlessly. This should be happily removed. See also: * <bb12396f91> * <https://reviews.llvm.org/D63024>
Please read the rustc-dev-guide chapter on Backend Agnostic Codegen.