FreeBSD does not have _GNU_SOURCE in util/strtod.c
But define it and it works as intended.
If not defined users with locales with "," as a decimal separator gets the numbers as strings e.g "0.33" all wrong. strtof calls strtof_l without the intended locale loc. src/util/strtod.c#L81 but with the acutal locale set by the user. returned by __get_locale() in freebsd soruce /usr/src/contrib/gdtoa/strtod.c:1085 the same applies to strtof it calls strof_l with __get_locale...
Also see freebsd bug 241506 and kde bug 399143 and freebsd bug 237662