[Clang] Fix using LTO with the new driver in RDC-mode

The new driver supports LTO for RDC-mode compilations. However, this was
not correctly handled for non-LTO compilations. HIP can handle this as
it is fed to `lld` which will perform the LTO itself. CUDA however would
require every work which is wholly useless in non-RDC mode so it should
report an error.

Reviewed By: yaxunl

Differential Revision: https://reviews.llvm.org/D135305