Merge remote-tracking branch 'afaerber/qom-cpu' into staging

Merge remote-tracking branch 'afaerber/qom-cpu' into staging

# By Igor Mammedov (21) and others
# Via Andreas Färber
* afaerber/qom-cpu: (29 commits)
  Drop redundant resume_all_vcpus() from main()
  cpus: Fix pausing TCG CPUs while in vCPU thread
  target-i386: Replace cpuid_*features fields with a feature word array
  target-i386: Break CPUID feature definition lines
  target-i386/kvm.c: Code formatting changes
  target-i386: Group together level, xlevel, xlevel2 fields
  pc: Implement QEMUMachine::hot_add_cpu hook
  QMP: Add cpu-add command
  Add hot_add_cpu hook to QEMUMachine
  target-i386: Move APIC to ICC bus
  target-i386: Attach ICC bus to CPU on its creation
  target-i386: Introduce ICC bus/device/bridge
  cpu: Move cpu_write_elfXX_note() functions to CPUState
  kvmvapic: Make dependency on sysbus.h explicit
  target-i386: Replace MSI_SPACE_SIZE with APIC_SPACE_SIZE
  target-i386: Do not allow to set apic-id once CPU is realized
  target-i386: Introduce apic-id CPU property
  target-i386: Introduce feat2prop() for CPU properties
  acpi_piix4: Add infrastructure to send CPU hot-plug GPE to guest
  cpu: Add helper cpu_exists(), to check if CPU with specified id exists
  ...