0x08 (BS) was treated as plain backspace alongside 0x7f (DEL). On
Windows Terminal, Backspace sends 0x7f and Ctrl+Backspace sends 0x08,
making ctrl+backspace bindings unreachable.
Now 0x08 matches ctrl+backspace (and ctrl+h, same byte) but not plain
backspace. 0x7f remains plain backspace.
fixes#2139