Searches for the last occurence of the given argument, testing for equality uses the following rule.
Searches for the last occurence of the given argument, testing for equality uses the following rule.If a specific compare function is specified for the list, this compare function is used.
Otherwise if the element size of the list is set to a positive value, the c-library function memcmp() is used.
Otherwise the element pointer specified is tested for equality with the elements of the list.