[lib] hash compare function arguments ought to be const qualified

[lib] hash compare function arguments ought to be const qualified

2008-08-14 Stephen Hemminger <stephen.hemminger@vyatta.com>

	* lib/hash.h: (struct hash) Hash comparator callback really
	  ought to treat storage behind arguments as constant - a compare
	  function with side-effects would be evil.
	* */*.c: Adjust comparator functions similarly, thus fixing at least
	  a few compiler warnings about const qualifier being dropped.

Signed-off-by: Paul Jakma <paul@quagga.net>