Merge remote-tracking branch 'remotes/berrange-gitlab/tags/sock-next-pull-request...

 - Fix inverted logic in abstract socket QAPI support
 - Only report abstract socket support in QAPI on Linux hosts
 - Expand test coverage
 - Misc other code cleanups

# gpg: Signature made Tue 03 Nov 2020 14:00:53 GMT
# gpg:                using RSA key DAF3A6FDB26B62912D0E8E3FBE86EBB415104FDF
# gpg: Good signature from "Daniel P. Berrange <dan@berrange.com>" [full]
# gpg:                 aka "Daniel P. Berrange <berrange@redhat.com>" [full]
# Primary key fingerprint: DAF3 A6FD B26B 6291 2D0E  8E3F BE86 EBB4 1510 4FDF

* remotes/berrange-gitlab/tags/sock-next-pull-request:
  sockets: Make abstract UnixSocketAddress depend on CONFIG_LINUX
  sockets: Bypass "replace empty @path" for abstract unix sockets
  char-socket: Fix qemu_chr_socket_address() for abstract sockets
  sockets: Fix socket_sockaddr_to_address_unix() for abstract sockets
  sockets: Fix default of UnixSocketAddress member @tight
  test-util-sockets: Test the complete abstract socket matrix
  test-util-sockets: Synchronize properly, don't sleep(1)
  test-util-sockets: Factor out test_socket_unix_abstract_one()
  test-util-sockets: Clean up SocketAddress construction
  test-util-sockets: Correct to set has_abstract, has_tight
  test-util-sockets: Plug file descriptor leak

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