Merge remote-tracking branch 'remotes/vivier2/tags/linux-user-for-upstream-pull-reque...

Merge remote-tracking branch 'remotes/vivier2/tags/linux-user-for-upstream-pull-request' into staging

# gpg: Signature made Mon 27 Feb 2017 22:15:47 GMT
# gpg:                using RSA key 0xF30C38BD3F2FBE3C
# gpg: Good signature from "Laurent Vivier <lvivier@redhat.com>"
# gpg:                 aka "Laurent Vivier <laurent@vivier.eu>"
# gpg:                 aka "Laurent Vivier (Red Hat) <lvivier@redhat.com>"
# Primary key fingerprint: CD2F 75DD C8E3 A4DC 2E4F  5173 F30C 38BD 3F2F BE3C

* remotes/vivier2/tags/linux-user-for-upstream-pull-request:
  syscall: fixed mincore(2) not failing with ENOMEM
  linux-user: fix do_rt_sigreturn on m68k linux userspace emulation
  linux-user: correctly manage SR in ucontext
  linux-user: Add signal handling support for x86_64
  linux-user: Add sockopts for IPv6 ping and IPv6 traceroute
  linux-user: fix fork()

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