Pass filename to 'wp_feed_cache_transient_lifetime' filer

[dd32]

Pass filename to 'wp_feed_cache_transient_lifetime' filer to allow for a per-hostname or per-url cache timeout.

For example, I may want local-feeds to receive a 1hour timeout, whilst leaving remote feeds as 12hours.

[westi]

(In [11787]) Pass the filename to the wp_feed_cache_transient_lifetime filter to give the plugins some context. Fixes #10565 props dd32.