The getDefaultSubtargetFeatures method of SubtargetFeature did actually return a

The getDefaultSubtargetFeatures method of SubtargetFeature did actually return a
string of features for that target. However LTO was using that string to pass
into the "create target machine" stuff. That stuff needed the feature string to
be in a particular form. In particular, it needed the CPU specified first and
then the attributes. If there isn't a CPU specified, it required it to be blank
-- e.g., ",+altivec". Yuck.

Modify the getDefaultSubtargetFeatures method to be a non-static member
function. For all attributes for a specific subtarget, it will add them in like
normal. It will also take a CPU string so that it can satisfy this horrible
syntax.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103451 91177308-0d34-0410-b5e6-96231b3b80d8