str to plain ASCII.
For best results,
str should be in composed normalised form.
This function performs a reasonably good set of character replacements. The particular set of replacements that is done may change by version or even by runtime environment.
If the source language of
str is known, it can used to improve the accuracy of the translation by passing it as
. It should be a valid POSIX locale string (of the form `language_territory[
from_locale is null then the current locale is used.
If you want to do translation for no specific locale, and you want it to be done independently of the currently locale, specify `"C"` for
the source locale, if known
a string, in UTF-8
a string in plain ASCII