[clang] [Sema] Provide `-fno-/-fvisibility-global-new-delete` option (PR #75364)

[Roland McGrath via cfe-commits]

frobtech wrote:

The meaning that we want to make clear is that this toggles the special behavior of forcing the visibility of these symbols despite all the other mechanisms that usually control visibility for all other symbols.  So perhaps `-fforced-global-new-delete-visibility` (or even `-fforced-global-new-delete-visibility=default`) describes the status quo ante, and `-fno-forced-global-new-delete-visibility` describes the new opt-in wherein these symbols are not treated differently than others. (The `=...` variant of the positive form would permit forcing to a different visibility than `default`, though I'm not sure there's a real need for that capability since in `-fno-forced-...` state the usual pragmas et al can arrange for that.)



https://github.com/llvm/llvm-project/pull/75364