Merge remote-tracking branch 'kwolf/tags/for-upstream' into staging

Block layer patches for 2.8.0-rc2

# gpg: Signature made Tue 29 Nov 2016 03:16:10 PM GMT
# gpg:                using RSA key 0x7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <[email protected]>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* kwolf/tags/for-upstream:
  docs: Specify that cache-clean-interval is only supported in Linux
  qcow2: Remove stale comment
  qcow2: Allow 'cache-clean-interval' in Linux only
  qcow2: Make qcow2_cache_table_release() work only in Linux

Message-id: 1480436227[email protected]
Signed-off-by: Stefan Hajnoczi <[email protected]>