Cache: create dependencies when closing macro

[vitkutny]

• bug fix? no
• BC break? no

prevents invalid expiration from dependencies callback when caching time-expensive data

example of code causing problem:

$dependencies = function () {
	return [Cache::Expiration => new DateTime('+1 second')];
};

{cache foo dependencies => $dependencies}
	{php sleep(2)} {* loading data *}
	bar
{cache}

current behaviour:
content is cached with zero expiration (-1 second)

expected behaviour:
content is cached for 1 second