The `dev=yes` and `production=yes` options work as aliases to set a number of
options, while still aiming to allow overriding specific options if the user
wishes so. (E.g. `production=yes use_lto=no` should work to enable production
defaults *but* disable LTO.)
That wasn't working as `ARGUMENTS.get()` returns a string and not a boolean as
expected by `BoolVariable`, and this wasn't flagged as a bug... So added a
helper method using SCons' `BoolVariable._text2bool` to do the conversion
manually.
92d59d0879