Merge remote-tracking branch 'remotes/vivier2/tags/linux-user-for-3.0-pull-request...

Merge remote-tracking branch 'remotes/vivier2/tags/linux-user-for-3.0-pull-request' into staging

Fixes in syscall numbers,
disable the build of binaries not needed for linux-user,
update of qemu-binfmt-conf.sh and cleanup around is_error()

# gpg: Signature made Tue 12 Jun 2018 11:57:18 BST
# gpg:                using RSA key F30C38BD3F2FBE3C
# 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-3.0-pull-request:
  linux-user/sparc64: Add inotify_rm_watch and tee syscalls
  linux-user/microblaze: Fix typo in accept4 syscall
  linux-user/hppa: Fix typo in mknodat syscall
  linux-user/alpha: Fix epoll syscalls
  qemu-binfmt-conf.sh: ignore the OS/ABI field
  linux-user: disable qemu-bridge-helper and socket_scm_helper build
  linux-user: Use is_error() to avoid warnings and make the code clearer
  linux-user: Export use is_error(), use it to avoid warnings

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