New code for 5.8: - Various cleanups to remove dead code, unnecessary conditionals, asserts, etc. - Fix a linker warning caused by xfs stuffing '-g' into CFLAGS redundantly. - Tighten up our dmesg logging to ensure that everything is prefixed with 'XFS' for easier grepping. - Kill a bunch of typedefs. - Refactor the deferred ops code to reduce indirect function calls. - Increase type-safety with the deferred ops code. - Make the DAX mount options a tri-state.