LC_NUMERIC fields, but only for *grouping fields - other fields are converted
to a chars in localeconv(), so final change is:
"-1" -> "127"
127 here is because CHAR_MAX supposed, which is _positive_ (SUSv2 requirement),
not negative as 255. It is still a bit of hack. To find real CHAR_MAX will be
better to sprintf() it once somewhere in static buffer. *grouping parsing
still broken and missing and needs to be implemented.