[clang-repl] Remove host assumptions from Interpreter/CUDA tests (#237794)
PR #236206 recently aadded tests in clang/test/Interpreter/CUDA that run
on any Linux host with the NVPTX target and JIT support, but these tests
have some assumptions that aren't true on some of the RISC-V buildbots:
* The stub libcudart.so is linked with the default linker, which fails
on hosts without one. This patch addresses this by linking with
-fuse-ld=lld and adding `REQUIRES: lld`, as clang/test/Driver does.
* The CHECK lines will break on targets such as RISC-V that add signext
to i32 returns and arguments. I've adjusted the CHECK lines to handle
this in a similar way to similar lines in Interpreter/emit-llvm.cpp.
Debugging the buildbot issues and searching the repo for similar
patterns in existing tests was LLM assisted.