[X86] In getHostCPUName, remove some code that changes some AMD CPU names...

[X86] In getHostCPUName, remove some code that changes some AMD CPU names based on features not being enabled.

The CPU name is really just used for scheduler and other microarchitectural optimizations. The feature flags should be determined by getHostCPUFeatures which should always be used with getHostCPUName. Trying to alter CPU name strings to control features just isn't practical.

Most of these types of things were removed from Intel CPUs a while ago.

This is part of my plan to bring compiler-rt's cpu_model.c file up to date with the equivalent functionality in libgcc. A lot of the code in that file is copied from Host.cpp and we want to keep them reasonably in sync.

llvm-svn: 307467