SDAG: Clean up dangling nodes in AArch64ISelDAGToDAG::SelectImpl
SDAG: Clean up dangling nodes in AArch64ISelDAGToDAG::SelectImpl

When we convert to the void Select interface, leaving unreferenced
nodes around won't be allowed anymore.

Part of llvm.org/pr26808.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@269345 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm