Merge remote-tracking branch 'remotes/ehabkost/tags/machine-next-pull-request' into staging

Machine queue, 2019-04-25

* 4.1 machine-types (Cornelia Huck)
* Support MAP_SYNC on pmem memory backends (Zhang Yi)
* -cpu parsing fixes and cleanups (Eduardo Habkost)
* machine initialization cleanups (Wei Yang, Markus Armbruster)

# gpg: Signature made Thu 25 Apr 2019 18:54:57 BST
# gpg:                using RSA key 2807936F984DC5A6
# gpg: Good signature from "Eduardo Habkost <ehabkost@redhat.com>" [full]
# Primary key fingerprint: 5A32 2FD5 ABC4 D3DB ACCF  D1AA 2807 936F 984D C5A6

* remotes/ehabkost/tags/machine-next-pull-request:
  util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap()
  linux-headers: add linux/mman.h.
  scripts/update-linux-headers: add linux/mman.h
  util/mmap-alloc: Add a 'is_pmem' parameter to qemu_ram_mmap
  cpu: Fix crash with empty -cpu option
  cpu: Rename parse_cpu_model() to parse_cpu_option()
  vl: Simplify machine_parse()
  vl: Clean up after previous commit
  vl.c: allocate TYPE_MACHINE list once during bootup
  vl.c: make find_default_machine() local
  hw: add compat machines for 4.1

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