Fail gracefully if no bin for cache_clear_all, but cid is set

Problem/Motivation

When try to cache_clear_all with $cid, but no $bin, no effect. The reason is the cache key is generated by $bin . '-' . $cid (e.g cache-foo) and since there is no bin details, the key become something like '-foo'. This details is in the docblock, of cache_clear_all, but code doesn't enforce it.

/**
 * Expires data from the cache.
...
...
 * @param $bin
 *   If set, the cache bin to delete from. Mandatory argument if $cid is set.
...
...
 */
function cache_clear_all($cid = NULL, $bin = NULL, $wildcard = FALSE) {

Proposed resolution

Solution 1. Provide default option to bin, if $cid is set.
Solution 2. If solution 1 is too much assumption, throw an exception for the calls with $cid and no $bin.

Remaining tasks

1. Discuss
2. Issue path

User interface changes

N/A

API changes

Depends on solution.