[compiler-rt] [compiler-rt][test][builtins] Check linker support for --start-group (PR #205610)

[Joel E. Denny via llvm-commits]

jdenny-ornl wrote:

> @quic-garvgupt I am just wondering if `COMPILER_RT_BAREMETAL_BUILD` works in this case.
> 
> Anyway, your suggested change works for us on AIX.
> 
> @jdenny-ornl Could you give it a try?

Sure, but please send a diff I can apply so I don't try the wrong thing.  Wouldn't the cmake result still be bypassed for nvptx?

https://github.com/llvm/llvm-project/pull/205610