MFC 264353,264509,264768,264770,264825,264846,264988,265114,265165,265365,
265941,265951,266390,266550,266910:
Various bhyve fixes:
- Don't save host's return address in 'struct vmxctx'.
- Permit non-32-bit accesses to local APIC registers.
- Factor out common ioport handler code.
- Use calloc() in favor of malloc + memset.
- Change the vlapic timer frequency to be in the ballpark of contemporary
  hardware.
- Allow the guest to read the TSC via MSR 0x10.
- A VMCS is always inactive when it exits the vmx_run() loop.  Remove
  redundant code and the misleading comment that suggest otherwise.
- Ignore writes to microcode update MSR.  This MSR is accessed by RHEL7
  guest.
  Add KTR tracepoints to annotate wrmsr and rdmsr VM exits.
- Provide an alias for the userboot console and name it 'comconsole'.
- Use EV_ADD to create an mevent and EV_ENABLE to enable it.
- abort(3) the process in response to a VMEXIT_ABORT.
- Don't include the guest memory segments in the bhyve(8) process core dump.
- Make the vmx asm code dtrace-fbt-friendly.
- Allow vmx_getdesc() and vmx_setdesc() to be called for a vcpu that is in
  the VCPU_RUNNING state.
- Enable VMX in the IA32_FEATURE_CONTROL MSR if it not enabled and the MSR
  isn't locked.