[clang] [flang] [clang][flang][driver] Correct program names in option group descriptions (PR #81726)

[David Spickett via cfe-commits]

DavidSpickett wrote:

To add program specific option help, my idea is to store mutliple strings in the driver and select based on who's asking for the help.

I think that warrants its own change so I'm not attempting that here. Also, there's only 2 flang options that refer to clang so it's not the priority here.

https://github.com/llvm/llvm-project/pull/81726