x86: Populate COMMON_CPUID_INDEX_80000001 for Intel CPUs [BZ #23459]

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

	[BZ #23459]
	* sysdeps/x86/cpu-features.c (get_extended_indices): New
	function.
	(init_cpu_features): Call get_extended_indices for both Intel
	and AMD CPUs.
	* sysdeps/x86/cpu-features.h (COMMON_CPUID_INDEX_80000001):
	Remove "for AMD" comment.