bug#69191: 30.0.50; New var `major-mode-remap-defaults`, for packages

[Stefan Monnier]

> The idea seems attractive, but what's going to happen in such
> a configuration when go-ts-mode.el hasn't been loaded yet, and go-mode is
> (without additional effort by the user) is not installed?

I'd expect that `go-ts-mode.el` would setup both `auto-mode-alist` and`
and `major-mode-remap-defaults` at the same time (probably at the same
time as the function's autoload), so I don't foresee any problem there.

[ There is a problem with `set-auto-mode` which may skip/ignore the
  `go-mode` specification before even looking it up in
  `major-mode-remap`, but that's in the process of being fixed
  as part of bug#67795.  ]


        Stefan