This patch implements .set dsp directive and sets appropriate feature bits.This directive is a counterpart of -mattr=dsp command line option with the exception that it does not influence elf header flags. The usage example is gives in test file.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202966 91177308-0d34-0410-b5e6-96231b3b80d8