[clang] [flang] [clang][Driver] Add the ability to specify that RPATH should be added by default (PR #115163)

[David Truby via cfe-commits]

DavidTruby wrote:

For what it’s worth, as a user I’m always surprised that this _isn’t_ the default. It’s quite annoying to eg have to set LD_LIBRARY_PATH when using openmp with clang when they’re built alongside each other. Is there a specific reason this isn’t the default or is it just historical?

https://github.com/llvm/llvm-project/pull/115163