This patch is in response to r223147 where the avaiable features are
computed based on ".cpu" directive. This will work clean for the standard
variants like cortex-a9. For custom variants which rely on standard cpu names
for assembly, the additional features of a CPU should be propagated. This can be
done via ".arch_extension" as long as the assembler supports it. The
implementation for krait along with unit test will be submitted in next patch.
llvm-svn: 230650
Sumanth Gundapaneni