rust-config: fix incorrect coercion of null values to false
As explained in the previous changeset:
Probably being too trigger happy about boolean values, I incorrectly set
the transform for a `None` to a `Some(false)`. It would cause for example
the `ui.formatted` value to be set to `Some(false)`, which turns off the colors
among other things, when `None` would trigger the automatic behavior.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
end_of_line = lf
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true
end_of_line = lf
[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false
end_of_line = lf