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.

It is not allowed by the spec and we incorrectly assumed chunked
and eventually timed out.  OK'd by phk@.
Fixes #1843.

We don't have forward declarations in VCL.  OK'd by phk@.
Fixes #1837.

Spotted by:	fgs

that we can continue.

Fixes #1849

can recurse.

a return value.

hyperwide memcmp()

In incredibly seldom circumstances this bug would cause ESI:include
data to be bad.

Fixes:	#1852

None of it was important or troubling.

Fixes #1851.

Dump boc's in panic output

need the busyobj at all now.

Dispose when refcount goes to zero.
Private objcores for pipe neither want nor need a boc, so make it optional.