There are a few places where subtarget features are still

There are a few places where subtarget features are still
represented by uint64_t, this patch replaces these
usages with the FeatureBitset (std::bitset) type.

Differential Revision: http://reviews.llvm.org/D10542

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@241058 91177308-0d34-0410-b5e6-96231b3b80d8