eliminate TargetLoweringObjectFileSparc in favor of a TAI hook.

eliminate TargetLoweringObjectFileSparc in favor of a TAI hook.
A TAI hook is appropriate in this case because this is just an
asm syntax issue, not a semantic difference. TLOF should model
the semantics of the section.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78498 91177308-0d34-0410-b5e6-96231b3b80d8