Remove dead code and an obsolete testcase.

The debug location is now unconditionally being set for each
instruction, so resetting the location at the beginning of each basic
block is redundant.

<rdar://problem/25772716>

Author: adrian-prantl

lib/IRGen/IRGenSIL.cpp

@@ -1632,14 +1632,6 @@ void IRGenSILFunction::visitSILBasicBlock(SILBasicBlock *BB) {
   DominanceScope dominance(*this, InEntryBlock ? DominancePoint::universal()
                                                : DominancePoint(BB));
 
-  // The basic blocks are visited in a random order. Reset the debug location.
-  std::unique_ptr<AutoRestoreLocation> ScopedLoc;
-  if (InEntryBlock)
-    ScopedLoc = llvm::make_unique<PrologueLocation>(IGM.DebugInfo, Builder);
-  else
-    ScopedLoc = llvm::make_unique<ArtificialLocation>(
-        CurSILFn->getDebugScope(), IGM.DebugInfo, Builder);
-
   // Generate the body.
   bool InCleanupBlock = false;
   bool KeepCurrentLocation = false;