[clang] [flang] [clang][driver] Use $ prefix with config file options to have them added after all of the command line options (PR #117573)

[Paul Osmialowski via cfe-commits]

pawosm-arm wrote:

> The subject (linker flags) is no longer accurate.
> 
> It's better to mention that Add $ for ....

Reworded

https://github.com/llvm/llvm-project/pull/117573