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

* remotes/riku/linux-user-for-upstream:
  linux-user: support the SIOCGIFINDEX ioctl
  linux-user: support the KDSIGACCEPT ioctl
  linux-user: allow NULL tv argument for settimeofday
  linux-user: respect timezone for settimeofday
  linux-user: fix struct target_epoll_event layout for MIPS
  linux-user: support strace of epoll_create1
  linux-user: allow NULL arguments to mount
  linux-user: support SO_PASSSEC setsockopt option
  linux-user: support SO_{SND, RCV}BUFFORCE setsockopt options
  linux-user: support SO_ACCEPTCONN getsockopt option
  linux-user: translate the result of getsockopt SO_TYPE
  linux-user: added fake open() for /proc/self/cmdline
  Add support for MAP_NORESERVE mmap flag.

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