Use an index into the segments object index instead of a pointer, to
avoid dealing with the temporary buffer used in the active segment.

Correctly count the various kinds of states objects can be in.

Only check the signature id inside the signature id field.

Don't load segments if the object index was not committed.

Reuse the temporary object index buffer.

Lock updates to ttl and ban, if in the active segment, to close
race against segment closing.



git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4272 d4fa192b-c00b-0410-8231-f00ffab90ce4