Have the driver pass CPU and target feature information to cc1as.

When creating the MCSubtargetInfo, the assembler driver uses the CPU and
feature string to construct a more accurate model of what instructions
are and are not legal.

rdar://10840476


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150273 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed