[PATCH] safety limits on refresh_pattern settings.

Just got reminded about the 32-bit wrap problem in refresh_pattern
min/max values.

Attached patch limits the values to 1 year (arbitrary based on rumours).
Checking for 32-bit wrap and setting the max 1 year limit instead of
cutting them to zero.

The expected outcome of this is actual caching by refresh_pattern when
people desperately set in/max to > a million minutes. Instead of a
silent always-stale verdict.

Amos

-- 
Please be using
   Current Stable Squid 2.7.STABLE9 or 3.1.5