Merge remote-tracking branch 'remotes/riku/linux-user-for-upstream' into staging

* remotes/riku/linux-user-for-upstream:
  linux-user: Fix error handling in target_to_host_semarray()
  linux-user: Implement BLKPG ioctl
  linux-user: Fix error handling in lock_iovec()
  linux-user/signal.c: Don't pass sigaction uninitialised sa_flags
  linux-user/elfload.c: Avoid calling g_free() on uninitialized data
  linux-user: sync syscall numbers upto 3.13

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