New APIs for guest inspection.

New APIs for guest inspection.

This commit converts (some of) the Perl inspection code to C and
makes it available through core APIs.  The new APIs are:

inspect-os        - Does the inspection, returns list of OSes
inspect-get-*     - Get results of the inspection

where '*' is one of:

  type            - 'windows' or 'linux'
  distro          - Linux distro
  arch            - architecture
  product-name    - long product name string
  major-version
  minor-version   - major.minor version of OS
  mountpoints     - get a list of the mountpoints
  filesystems     - get all filesystems associated with the OS

This works for all existing supported Linux and Windows OSes.