Revert "CacheControl: Real fix for max_age and s_maxage"

This reverts commit f161926bea810159ec0b72c7539e6f57da66d707.

This seems to have been superceded by https://github.com/jech/polipo/commit/5b1a11faa6dc9c6b7e8c5673c21c3b45a4ecd717