In any case, that's ugly and thread-safe. The proper solution would
be to reimplement an atof() version that is locale-independant and
use in the many places that expect C/American float numbers. Even
then, there might be some buggy underlying libraries breakage
(e.g. Live555 ?).

Tested on Linux (both UTF-8 and Latin-x locales).
Needs testing on Win32.