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

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

Block layer patches

# gpg: Signature made Thu 29 Sep 2016 14:11:30 BST
# gpg:                using RSA key 0x7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74  56FE 7F09 B272 C88F 2FD6

* remotes/kevin/tags/for-upstream:
  oslib-posix: add a configure switch to debug stack usage
  coroutine-sigaltstack: use helper for allocating stack memory
  coroutine-ucontext: use helper for allocating stack memory
  coroutine: add a macro for the coroutine stack size
  coroutine-sigaltstack: rename coroutine struct appropriately
  oslib-posix: add helpers for stack alloc and free
  block: Remove qemu_root_bds_opts
  block: Move 'discard' option to bdrv_open_common()
  block: Use 'detect-zeroes' option for 'blockdev-change-medium'
  block: Parse 'detect-zeroes' in bdrv_open_common()
  block/qapi: Move 'aio' option to file driver
  block/qapi: Use separate options type for curl driver
  block: Drop aio/cache consistency check from qmp_blockdev_add()
  block: Fix error path in qmp_blockdev_change_medium()
  block-backend: remove blk_flush_all
  qemu: use bdrv_flush_all for vm_stop et al
  block: reintroduce bdrv_flush_all

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>