http: call git_inflate_end() when releasing http_object_request

http: call git_inflate_end() when releasing http_object_request

In new_http_object_request(), we initialize the zlib stream with
git_inflate_init(). We must have a matching git_inflate_end() to avoid
leaking any memory allocated by zlib.

In most cases this happens in finish_http_object_request(), but we don't
always get there. If we abort a request mid-stream, then we may clean it
up without hitting that function.

We can't just add a git_inflate_end() call to the release function,
though. That would double-free the cases that did actually finish.
Instead, we'll move the call from the finish function to the release
function. This does delay it for the cases that do finish, but I don't
think it matters. We should have already reached Z_STREAM_END (and
complain if we didn't), and we do not record any status code from
git_inflate_end().

This leak is triggered by t5550 at least (and probably other dumb-http
tests).

I did find one other related spot of interest. If we try to read a
previously downloaded file and fail, we reset the stream by calling
memset() followed by a fresh git_inflate_init(). I don't think this case
is triggered in the test suite, but it seemed like an obvious leak, so I
added the appropriate git_inflate_end() before the memset() there.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>