ALLOW_SOURCE_PING

[Amos Jeffries]

Checking to see what options to test my latest ping changes with, I 
discover ALLOW_SOURCE_PING is never defined or configured.

According to 
http://www.squid-cache.org/mail-archive/squid-dev/200304/0084.html its 
no longer used.

While I'm upgrading the pinger: does anyone know of a reason for not 
dropping ALLOW_SOURCE_PING it completely out of the code?

Amos