The SRAT table can contain information about processors that 0 A.D. doesn't have access to. Since processors are listed by calling the CPUID instruction on each processor, this list is not necessarily complete (and we really don't care about cores we don't have access to).
One part of the hardware detection code assumes that the processors in the SRAT are supposed to be known, which is not always the case (we have access to the whole SRAT table). This patch removes that assumption, and adds an early return for aesthetics.