util: Use XSI-compliant strerror_r() for FreeBSD.
util: Use XSI-compliant strerror_r() for FreeBSD.

The XSI-compliant variant of strerror_r returns an int indicating
success or failure, rather than a pointer to the error message string.

OpenSCAP/openscap,OpenSCAP/openscap,OpenSCAP/openscap,OpenSCAP/openscap,OpenSCAP/openscap,OpenSCAP/openscap