cases dealing with oc's without a boc duing fill-up.

All objcores, also for synth and req.body are now born with a boc,
which must of course be properly disposed of.

More assertive LRU code.

To get JSON back, the first argument must be "-j".

Currently only "help -j" is implemented, but that
will helpfully tell you which commands support
json output.

All JSON output has the form:

	[ version#, [<cli_command>],
		stuff
	]

For instance:

	[ 1, ["help", "-j"],
	  {
	  "request": "help",
	  "syntax": "help [<command>]",
	  "help": "\tShow command/protocol help.",
	  "minarg": 0, "maxarg": 1, "flags": "", "json": true
	  },
	  {
	  "request": "ping",
	  "syntax": "ping [<timestamp>]",
	  "help": "\tKeep connection alive.",
	  "minarg": 0, "maxarg": 1, "flags": "", "json": false
	  },
	  ...
	]

The string quoting for weird characters in JSON is XXX incomplete.

Prodded for by:	Kristian

overloading the LRUs list.

and end random code mucking about with it.

Some submitted by: github::sublimino

Rename Obj[GS]etattr() to ..Attr

Add ObjHasAttr() for cheap existence check on OAs.

When we fork the worker process, we close all filedescriptors we
have not explictly marked for it to inherit, for security reasons.

Operating system libraries may have open filedescriptors (see
end*ent(3)) and there is no way to chase these down.

At least on OSX something related to DNS lookups leaves such
a FD around, and when that code later discovers the FD doesn't
work, it closes it, even though it no longer owns it.

In ticket 1841, that happens to be FD7 which is one of our kqueue FDs.

Normally such library code should set 'close-on-exec' status with
fcntl(2) but that doesn't seem to be the case here, and this bit
of wisdom seems neglegted about 50/50, so it probably wouldn't
help us to examine this.

The fix here is to close the FDs, and replace them with a FD open
to /dev/null, so that there is no risk of information leak, but we
don't reuse the FD for something else until the library has properly
closed it.

Fixes #1841

Prompted by someone on #varnish.  OK'd by phk.