Add nuke_limited counter(Number of times reached nuke_limit.)

[kokoniimasu]

Hi,

I got a strange error the other day.
Status code is 200, but body was incomplete.
This error occurred because nuke_limit was reached.(It does not 503,
because beresp.do_stream=true is default)
I think this error is hard to notice.
I would like to add a new counter to make notice it.

https://github.com/xcir/varnish-cache/commit/3a1f45d05dcdc0d22a71148c25ae2dedcf93e6ea

I think it can see that need to increase nuke_limit by this counter.
Can I get your opinion?

Regards,
--
Shohei Tanaka(@xcir)
http://blog.xcir.net/ (JP)