The defines in idlib/Str.h won't be set to redirect the low
level c string functions to idStr when IDSTR_NO_REDIRECT is
set.
Fixes compilation for MSVC:
error C2761: 'Cmp' : member function redeclaration not allowed
Reported by spiral.
Get rid of the 2 CPUID flags and combine them with SSE in one
implementation.
SSE flags can now be set on all x86 and x86_64 platforms -
independent of -ffast-math.
Helper defines borrowed from STREFLOP.
