Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

Pull request

v2:
 * Fixed stray slirp submodule change [Peter]

Fixes for the lock guard macros, code conversions to the lock guard macros, and
support for selecting fuzzer targets with argv[0].

# gpg: Signature made Mon 04 May 2020 16:11:11 BST
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  lockable: Replace locks with lock guard macros
  lockable: replaced locks with lock guard macros where appropriate
  lockable: fix __COUNTER__ macro to be referenced properly
  fuzz: select fuzz target using executable name

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