gzipread: ensure we get the last out of the zlib buffer on close
gzipread: ensure we get the last out of the zlib buffer on close

As reported in issue #387, and demonstrated by the added gzip test in
previous commit, closing a gzip stream would loose all pending data in
the zlib buffers.  Ensure we call inflate with our clear intention to
end our business, thus flush whatever there is to produce.

Signed-off-by: Fabian Groffen <2c4829061e3ecacc1da315323749610b9ffaef65@gentoo.org>

grobian/carbon-c-relay,grobian/carbon-c-relay,grobian/carbon-c-relay