Add high-level CPUID wrapper.

In i386 and x86-64 cpu units, add a

function CPUID(in_eax: uint32; in_ecx: uint32 = 0): TCpuidResult;

where

type
    TCpuidResult = record
      eax, ebx, ecx, edx: uint32;
    end;

used by the rest of the unit and usable from outside, and also add a

function GetProcessorBrandString: shortstring;

and use it in recent blea.pp in place of the ad hoc horror it does presently.