public: export x86 cpu featureset information in the public API

public: export x86 cpu featureset information in the public API

For the featureset to be a useful object, it needs a stable interpretation, a
property which is missing from the current hw_caps interface.

Additionly, introduce TSC_ADJUST, FDP_EXCP_ONLY, SHA, PREFETCHWT1, ITSC, EFRO
and CLZERO which will be used by later changes.

To maintain compilation, FSCAPINTS is currently hardcoded at 9.  Future
changes will change this to being dynamically generated.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>