Merge remote-tracking branch 'remotes/riku/tags/pull-linux-user-20160225' into staging

Second pull req with getrandom fix

# gpg: Signature made Thu 25 Feb 2016 10:57:42 GMT using RSA key ID DE3C9BC0
# gpg: Good signature from "Riku Voipio <riku.voipio@iki.fi>"
# gpg:                 aka "Riku Voipio <riku.voipio@linaro.org>"

* remotes/riku/tags/pull-linux-user-20160225:
  linux-user: add getrandom() syscall
  linux-user: correct timerfd_create syscall numbers
  linux-user: remove unavailable syscalls from aarch64
  linux-user: sync syscall numbers with kernel
  linux-user: Don't assert if guest tries shmdt(0)
  linux-user: set ppc64/ppc64le default CPU to POWER8
  build: [linux-user] Rename "syscall.h" to "target_syscall.h" in target directories
  linux-user: fix realloc size of target_fd_trans.

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