[X86] Add CPU name strings to getIntelProcessorTypeAndSubtype and...

[X86] Add CPU name strings to getIntelProcessorTypeAndSubtype and getAMDProcessorTypeAndSubtype in compiler-rt.

These aren't used in compiler-rt, but I plan to make a similar
change to the equivalent code in Host.cpp where the mapping from
type/subtype is an unnecessary complication. Having the CPU strings
here will help keep the code somewhat synchronized.