Add the new shm_ino field to struct shmfd.  Missed in 270823.

Reported by:	peter
Pointy hat to:	jhb
MFamd64: Add a machdep.bootmethod sysctl to inform the installer which
firmware method was used for booting.  This is hardcoded to BIOS on i386.

PR:		192962
Reviewed by:	nwhitehorn
MFC after:	1 week
Fix a typo.
- Add a new structure type for the ACPI 3.0 SMAP entry that includes the
  optional attributes field.
- Add a 'machdep.smap' sysctl that exports the SMAP table of the running
  system as an array of the ACPI 3.0 structure.  (On older systems, the
  attributes are given a value of zero.)  Note that the sysctl only
  exports the SMAP table if it is available via the metadata passed from
  the loader to the kernel.  If an SMAP is not available, an empty array
  is returned.
- Add a format handler for the ACPI 3.0 SMAP structure to the sysctl(8)
  binary to format the SMAP structures in a readable format similar to
  the format found in boot messages.

MFC after:	2 weeks
Rename shm_dict_init to shm_init to fix a compiler warning.

Reviewed by:	jhb