606d9c0c0e
This was originally introduced in #10916 as a way to remove all landing pads when performing LTO. However this is no longer necessary today since rustc properly marks all functions and call-sites as nounwind where appropriate. In fact this is incorrect in the presence of `extern "C-unwind"` which must create a landing pad when compiled with `-C panic=abort` so that foreign exceptions are caught and properly turned into aborts.
Please read the rustc-dev-guide chapter on Backend Agnostic Codegen.