Convert a return code integer to a text string. This string can be
used to output a diagnostic message to the user.
TLD_SUCCESS
Successful operation. This value is guaranteed to
always be zero, the remaining ones are only guaranteed to hold
non-zero values, for logical comparison purposes.
TLD_INVALID
Invalid character found.
TLD_NODATA
No input data was provided.
TLD_MALLOC_ERROR
Error during memory allocation.
TLD_ICONV_ERROR
Error during iconv string conversion.
TLD_NO_TLD
No top-level domain found in domain string.
RETURN VALUE
Returns a pointer to a statically allocated string
containing a description of the error with the return code rc.
