The memory leak was caused by a bug in function setlocale on FreeBSD:
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=243195
The fix is the following:
* Remove the calls to setlocale when formatting the result.
* The function snprintf is still called, and then is now locale dependent,
for example in French the decimal separator is a comma instead of a dot.
* A new function calc_sanitize_decimal_number is introduced to "sanitize" a
decimal number: keep only the decimal separator (replace it by a dot) and
remove any other separator found.
Unit tests are added on these functions:
* calc_sanitize_decimal_number
* calc_format_result
Sébastien Helleu