Merge remote-tracking branch 'remotes/vivier2/tags/linux-user-for-6.2-pull-request' into staging

Pull request linux-user 20210916

Code cleanup

# gpg: Signature made Thu 16 Sep 2021 16:11:58 BST
# gpg:                using RSA key CD2F75DDC8E3A4DC2E4F5173F30C38BD3F2FBE3C
# gpg:                issuer "laurent@vivier.eu"
# gpg: Good signature from "Laurent Vivier <lvivier@redhat.com>" [full]
# gpg:                 aka "Laurent Vivier <laurent@vivier.eu>" [full]
# gpg:                 aka "Laurent Vivier (Red Hat) <lvivier@redhat.com>" [full]
# Primary key fingerprint: CD2F 75DD C8E3 A4DC 2E4F  5173 F30C 38BD 3F2F BE3C

* remotes/vivier2/tags/linux-user-for-6.2-pull-request:
  linux-user: Check lock_user result for ip_mreq_source sockopts
  linux-user: Drop unneeded includes from qemu.h
  linux-user: Don't include gdbstub.h in qemu.h
  linux-user: Split linux-user internals out of qemu.h
  linux-user: Split safe-syscall macro into its own header
  linux-user: Split mmap prototypes into user-mmap.h
  linux-user: Split loader-related prototypes into loader.h
  linux-user: Split signal-related prototypes into signal-common.h
  linux-user: Split strace prototypes into strace.h
  linux-user: Fix coding style nits in qemu.h

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